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M.C.Q. [1 Marks Each]

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MCQ 11 Mark
If two adjacent angles are equal, then each angle measures $90^\circ .$
  • A
    True
  • False
  • C
    Ambiguous
  • D
    Data Insufficient
Answer
Correct option: B.
False

 Answer is $(B)$
If two adjacent angles measures $90$ degrees only when lines are perpendicular to each other.
hence the above statement is False.

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MCQ 21 Mark
If an angle is its own complementary angle, then its measure is _________.
  • A
    $30^\circ $
  • $45^\circ $
  • C
    $60^\circ $
  • D
    $90^\circ $
Answer
Correct option: B.
$45^\circ $

 Let the angle be $X$ It is given that $X$ is its own complementary angle.
$\Rightarrow X + X = 90^\circ $
$\Rightarrow 2X = 90^\circ $
$\Rightarrow X = 45^\circ $

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MCQ 31 Mark
Supplementary angle of $100^\circ $ is:
  • A
    $180^\circ $
  • B
    $90^\circ $
  • $80^\circ $
  • D
    $60^\circ $
Answer
Correct option: C.
$80^\circ $

 Supplementary angles are two angles that have a sum of $180^\circ .$
The given supplementary angle is $100^\circ $ and we have to find other.
$\Rightarrow $ Supplementary angle $= 180^\circ - 100^\circ = 80^\circ .$
$\therefore$ Supplementary angle of $100^\circ $ is $80^\circ .$

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MCQ 41 Mark
Find the measure of the complementary angle of $90^\circ .$
  • $0^\circ$
  • B
    $45^\circ$
  • C
    $90^\circ$
  • D
    $60^\circ$
Answer
Correct option: A.
$0^\circ$

The pair of angles is said to be complementary, when their sum is $90^\circ .$
Let $x, y$ be any two complementary angles and $\text{m}(\angle{\text{x}})=90^\circ$
$\Rightarrow\text{m}(\angle{\text{x}})+\text{m}(\angle{\text{y}})=90^\circ.....$ (By definition of complementary angles)
$\Rightarrow90^\circ+\text{m}(\angle\text{y})=90^\circ$
$\Rightarrow\text{m}(\angle{\text{y}})=0^\circ$
Hence, measure of complementary angle of $90^\circ $ is $0^\circ .$

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MCQ 51 Mark
Consider the following statements relating to $3$ lines $L_1​ , L_2​$​ and $L_3​$ in the same plane
$1.$ If $L_2$ and $L_3​$​ are both parallel to $L_1​,$ then they are parallel to each other.
$2.$ If $L_2​$​ and $L_3$ are both perpendicular to $L_1​,$​ then they are parallel to each other.
$3.$ If the acute angle between $L_1​$​​​​​​​​ and $L_2$​​​​​​​​ is equal to to acute angle between $L_1​$​​​​​​​ and $L_3$, then $L_2​$​​​​​​​​ is parallel to $L_3​$​​​​​​​​.
Of these statements:
  • $(1)$ and $(2)$ are correct
  • B
    $(1)$ and $(3)$ are correct
  • C
    $(2)$ and $(3)$ are correct
  • D
    $(1), (2)$ and $(3)$ are correct
Answer
Correct option: A.
$(1)$ and $(2)$ are correct
$(1)$ and $(2)$ are correct
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MCQ 61 Mark
Two complementary angles are such that two times the measure of one is equal to three times the measure of the other. The measure of the larger angle is:
  • A
    $72^\circ$
  • B
    $108^\circ$
  • C
    $36^\circ$
  • $54^\circ$
Answer
Correct option: D.
$54^\circ$

Let the complementary angles be $x$ and $(90^\circ − x).$
Then, $2x = 3(90^\circ − x)$
$\Rightarrow2{\text{x}}=270^\circ-3\text{x}$
$\Rightarrow5\text{x}=270^\circ$
$\Rightarrow\text{x}=\frac{270^\circ}{5}=54^\circ$
$\therefore$ The two angles are $54^\circ , 36^\circ $

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MCQ 71 Mark
Find the angle which measure twice of its supplement.
  • A
    $100$
  • B
    $110$
  • $120$
  • D
    $130$
Answer
Correct option: C.
$120$

 Let the required angle be $x,$ then its supplement $= (180 - x)$ and $x = 2(180 - x)$
So, $(180 - x) + 2(180 - x) = 180$
$\Rightarrow 180 - x + 360 - 2x = 180$
$\Rightarrow -3x + 360 = 0$
$\Rightarrow -3x = -360$
$\Rightarrow 3x = 360$
$\Rightarrow x = 120^\circ $

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MCQ 81 Mark
The angles $x$ and $90^\circ – x$ are:
  • A
    Supplementary.
  • Complementary.
  • C
    Vertically opposite.
  • D
    Making a linear pair.
Answer
Correct option: B.
Complementary.

Sum of the given angles $= x + 90^\circ – x = 90^\circ $
Since, the sum of given two angles is $90^\circ $
Hence, they are complementary to each other.

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MCQ 91 Mark
Find the measure of an angle which is one - fifth of its supplement.
  • A
    $15^\circ $
  • $30^\circ$
  • C
    $45^\circ$
  • D
    $60^\circ $
Answer
Correct option: B.
$30^\circ$

Let the desired angle be $x.$
According to the question,
$\Rightarrow\text{x}=\frac{1}{5}(180-\text{x})$
$\Rightarrow6\text{x}=180$
$\Rightarrow\text{x}=30^\circ$

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MCQ 101 Mark
The sum of an angle and one third of its supplementary angle is $90^\circ$. The measure of the angle is:
  • A
    $135^\circ$
  • B
    $120^\circ$
  • C
    $60^\circ$
  • $45^\circ$
Answer
Correct option: D.
$45^\circ$

Let the required angle be $x$
Now, supplementary of the required angle $= 180^\circ- x$
Then,
$\text{x}+\frac{1}{3}(180^\circ-\text{x})=90^\circ$
$\Rightarrow 3\text{x}+180^\circ-\text{x}=270^\circ$
$\Rightarrow 2\text{x}=90^\circ$
$\Rightarrow \text{x}=45^\circ$
Hence, the correct answer is option $(d).$

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MCQ 111 Mark
Line $A$ is parallel to line $B ,$ line $C$ is perpendicular to line $A,$ Line $D$ is perpendicular to line $A.$Which statement below must also be true$ ?$
  • A
    Line $C$ is perpendicular to line $D$
  • Line $C$ is perpendicular to line $B$
  • C
    Line $A$ is perpendicular to line $B$
  • D
    Line $A$ is perpendicular to line $D$
Answer
Correct option: B.
Line $C$ is perpendicular to line $B$
Line $C$ is perpendicular to line $B$
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MCQ 121 Mark
In Fig. $POR$ is a line. The value of a is:
  • $40^\circ$
  • B
    $45^\circ$
  • C
    $55^\circ$
  • D
    $60^\circ$
Answer
Correct option: A.
$40^\circ$

Since, $POR$ is a line. So, the sum of angles forming linear pair is $180^\circ .$
$\therefore\angle\text{POQ}=\angle\text{ROQ}=180^\circ$
$\Rightarrow(3\text{a}+5)^\circ+(2\text{a}-25^\circ)=180^\circ$
$\Rightarrow3\text{a}+5^\circ+2\text{a}-25^\circ=180^\circ$
$\Rightarrow5\text{a}-20^\circ=180^\circ$
$\Rightarrow5\text{a}=180^\circ+20^\circ$
$\Rightarrow5\text{a}=200^\circ$
$\Rightarrow\text{a}=\frac{200^\circ}{5}$
$\Rightarrow\text{a}=40^\circ$
Hence, the value of a is $40^\circ .$

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MCQ 131 Mark
Two angles are supplementary and one angle is twice the other angle then, find the both angles.
  • A
    $110^\circ , 55^\circ $
  • $60^\circ , 120^\circ$
  • C
    $70^\circ , 140^\circ$
  • D
    $45^\circ , 90^\circ$
Answer
Correct option: B.
$60^\circ , 120^\circ$

Let one angle be $x^\circ $
then other angle is $2x^\circ ($As twice of one angle$)$
Since two angles are supplementary
$x^\circ + 2x^\circ = 180^\circ $
$3x^\circ = 180^\circ $
$\text{x}=\frac{180}{3}=60^\circ$
One angle is $60^\circ ,$
Other angle $2x^\circ = 2 \times 60^\circ = 120^\circ $

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MCQ 141 Mark
Vertically opposite angles are always:
  • A
    Supplementary
  • B
    Complementary
  • C
    Adjacent
  • Equal
Answer
Correct option: D.
Equal
By, property of vertically opposite angles, Vertically opposite angles are always equal.
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MCQ 151 Mark
If one angle of a linear pair is acute, then its other angle will be ______.
  • Obtuse angle
  • B
    Acute angle
  • C
    Right angle
  • D
    None of these
Answer
Correct option: A.
Obtuse angle

Linear pair of angles are supupsupplementary ie they add up to form $180$ degrees.
Hence one angle of linear pair is acute, other has to be obtuse angle.

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MCQ 161 Mark
How many degrees are there in an angle which equals one - fifth of its supplement$?$
  • A
    $15^\circ$
  • $30^\circ$
  • C
    $75^\circ$
  • D
    $150^\circ$
Answer
Correct option: B.
$30^\circ$

 Two angles which are supplementary add upto $180 .....(1)$
Let one angle be $x$ and other be $\frac{1}{5}\text{x}$
Hence, $\text{x}+\frac{1}{5}\text{x}=180....$ From $(1)$
$\Rightarrow\frac{6}{5}\text{x}=180$
$\Rightarrow\text{x}=180\times\frac{5}{6}=150$
Thus one angle is $150$ and the other angle is
$\frac{150}{5}=30^\circ$

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MCQ 171 Mark
In Fig. the value of $x$ is:
  • A
    $75$
  • $65$
  • C
    $45$
  • D
    $55$
Answer
Correct option: B.
$65$

$\angle \text{AOC}$ and $\angle \text{BOC}=180^\circ$ [$\because$ Linear pair angles]
$\Rightarrow 44^\circ+(2\text{x}+6)^\circ=180^\circ$
$\Rightarrow (2\text{x+6})^\circ=136^\circ$
$\Rightarrow 2\text{x}+6=136$
$\Rightarrow 2\text{x}=130$
$\Rightarrow \text{x}=65$
Hence, the correct answer is option $(b).$

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MCQ 181 Mark
An angle is $14^\circ $ more than its complementary angle, then angle is:
  • A
    $38^\circ$
  • $52^\circ$
  • C
    $50^\circ$
  • D
    None of these
Answer
Correct option: B.
$52^\circ$

Let the angle be $\angle{\text{x}}$
Thus, according to the question,
$x = 14 + 90 - x$
$\Rightarrow 2x = 104$
$\Rightarrow x = 52$
Therefore, the angle is $52^\circ .$

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MCQ 191 Mark
Find the measure of the supplementary angle of $132^\circ .$
  • $48^\circ$
  • B
    $32^\circ$
  • C
    $42^\circ$
  • D
    $38^\circ$
Answer
Correct option: A.
$48^\circ$
Two angles are supplementary when they add up to form $180$ degrees.
If one angle $= 132$
Let the other angle be $x$
Hence $x = 180 -132$
$= 48$
Hence supplementary angle of the following angle is $48$
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MCQ 201 Mark
The angle which is one - fifth of its complement is:
  • $15^\circ$
  • B
    $30^\circ$
  • C
    $45^\circ$
  • D
    $60^\circ$
Answer
Correct option: A.
$15^\circ$
We need to find out Angle which is $\frac{1}{5}$ of its complement is:
Let, the angle be $x$
$\therefore$ Its complement is $(90 - x)$ According to the question,
$\text{x}=\frac{1}{5}\times(90-\text{x})\text{x}=18-\frac{\text{x}}{5}$
​Now, $\text{x}+\frac{\text{x}}{5}=18$
$\therefore\frac{5\text{x}+\text{x}}{5}=18$
or $\frac{6\text{x}}{5}=18$
or $6\text{x}=90$
$\therefore\text{x}=15^\circ$
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MCQ 211 Mark
In Fig. if $AOB$ and $COD$ are straight lines, then:
  • A
    $x = 29, y = 100$
  • B
    $x = 110, y = 29$
  • $x = 29, y = 110$
  • D
    $x = 39, y = 110$
Answer
Correct option: C.
$x = 29, y = 110$
$\angle \text{AOD}+\angle \text{BOD}=180^\circ$ [Linear pair angles]
$\Rightarrow \text{y}^\circ+70^\circ=180^\circ$
$\Rightarrow \text{y}^\circ=110^\circ$
$\Rightarrow \text{y}=110$
Now, $\angle \text{AOC}= \angle \text{BOD}=70^\circ$ [Vertically opposite angles]
Now, $\angle \text{AOC}+\angle \text{COE}+\angle \text{EOB}+\angle \text{BOD}+\angle \text{AOD}=360^\circ$ [Complete angle]
$\Rightarrow 70^\circ+28^\circ+(3\text{x}-5)^\circ+70^\circ+110^\circ=360^\circ$
$\Rightarrow (3\text{x})^\circ+273^\circ=360^\circ$
$\Rightarrow3\text{x}=87$
$\Rightarrow \text{x}=29$
Hence, the correct answer is option $(c).$
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MCQ 221 Mark
In Fig. $a$ and $b$ are:
  • A
    Alternate exterior angles.
  • B
    Corresponding angles.
  • Alternate interior angles.
  • D
    Vertically opposite angles.
Answer
Correct option: C.
Alternate interior angles.
In the given figure, $a$ and $b$ are alternate interior angles as both lie on opposite sides of transverse line.
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MCQ 231 Mark
The pair of complementary angles from the following options are:
  • A
    $30^\circ , 150^\circ$
  • B
    $76^\circ , 14^\circ$
  • $65^\circ , 65^\circ$
  • D
    $120^\circ , 30^\circ$
Answer
Correct option: C.
$65^\circ , 65^\circ$

Complementary angles are those, whose measures add up to $90^\circ $ Out of the given options,
$30+150=180^\circ\neq90^\circ76+14=90^\circ\\65+65=130^\circ\neq90^\circ120+30=150^\circ\neq90^\circ$

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MCQ 241 Mark
Lines $PQ$ and $RS$ intersect at $O.$ If $\angle\text{POR}$ is three times $\angle\text{ROQ}$, then $\angle\text{SOQ}$ is:
  • A
    $120^\circ$
  • B
    $150^\circ$
  • $135^\circ$
  • D
    $45^\circ$
Answer
Correct option: C.
$135^\circ$

$\angle\text{POR}=3\angle\text{ROQ}$ (Given)
$\angle\text{POR}+\angle\text{ROQ}=180^\circ$
$\Rightarrow3\angle\text{ROQ}+\angle\text{ROQ}=180^\circ$
$\Rightarrow4\angle\text{ROQ}=180^\circ$
$\Rightarrow\text{ROQ}=\frac{180^\circ}{4}=45^\circ$
Now, $\angle\text{SOQ}=\angle\text{POR}$
$=3\angle\text{ROQ }(\text{Ver. opp.}{\angle\text{S}})$
$=3\times45^\circ=135^\circ$

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MCQ 251 Mark
If two supplementary angles are in the ratio $2 : 7,$ then the angles are:
  • A
    $35^\circ , 145^\circ $
  • B
    $70^\circ , 110^\circ $
  • $40^\circ , 140^\circ$
  • D
    $50^\circ , 130^\circ$
Answer
Correct option: C.
$40^\circ , 140^\circ$

Let the angles be $2x$ and $7x$
Angles are given supplementary $2x + 7x = 180^\circ $
$9x = 180^\circ $
$x = 20^\circ $
So the angles are $2 \times 20^\circ = 40^\circ $ and $7 \times 20^\circ = 140^\circ $

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MCQ 261 Mark
Find the measure of the supplementary angle of $138^\circ .$
  • A
    $48^\circ$
  • $42^\circ$
  • C
    $52^\circ$
  • D
    $38^\circ$
Answer
Correct option: B.
$42^\circ$
Two angles are supplementary when they add upto form $180^\circ .$
Given, one angle $= 138.$
Let the supplement angle be $x.$
Hence, $x = 180 - 138 = 42^\circ $
Hence, supplementary angle of the following angle is $42^\circ .$
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MCQ 271 Mark
Two adjacent angles whose sum is $180$ is called:
  • A
    Complementary angles
  • Linear pair
  • C
    Vertically opposite angles
  • D
    None
Answer
Correct option: B.
Linear pair
The adjacent angles whose sum is $180$ degrees is called linear pair.
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MCQ 281 Mark
Find the angle which is $56^\circ$ more than its complement.
  • A
    $22^\circ$
  • B
    $63^\circ$
  • $73^\circ$
  • D
    $33^\circ$
Answer
Correct option: C.
$73^\circ$

Let unknown angle be $x^\circ .$
$\therefore$ Complement of $x = 90^\circ - x$
Acc to question,
$(90 - x)^\circ - x = 56^\circ $
$90^\circ - 2x = 56^\circ $
$-2x = -34^\circ $
$x = 17^\circ $
$\therefore (90 - x) = 90^\circ - 17^\circ = 73^\circ $

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MCQ 291 Mark
A line $AB$ is parallel to the line $CD$ This is symbolically written as
  • A
    $\overleftrightarrow{\text{AB}}\neq\overleftrightarrow{\text{CD}}$
  • B
    $\overleftrightarrow{\text{AB}}-\overleftrightarrow{\text{CD}}$
  • C
    $\overleftrightarrow{\text{AB}}\perp\overleftrightarrow{\text{CD}}​​$
  • $\overleftrightarrow{\text{AB}}\parallel\overleftrightarrow{\text{CD}}$
Answer
Correct option: D.
$\overleftrightarrow{\text{AB}}\parallel\overleftrightarrow{\text{CD}}$

A Line $AB$ is parallel to the line $CD.$
This is symbolically written as
$\overleftrightarrow{\text{AB}}\parallel\overleftrightarrow{\text{CD}}$

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MCQ 301 Mark
If the sum of two adjacent angles is $100^\circ $ and one of them is $35^\circ ,$ then the other is :
  • A
    $70^\circ$
  • $65^\circ$
  • C
    $135^\circ$
  • D
    $145^\circ$
Answer
Correct option: B.
$65^\circ$

Let the other angle be $x$
Now their sum $= 100^\circ $
$\Rightarrow x + 35^\circ = 100^\circ $
$\Rightarrow x = 100^\circ - 35^\circ = 65^\circ $
So the other angle is $65^\circ $

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MCQ 311 Mark
If angles of a linear pair are equal, then the measure of each angle is:
  • A
    $30^\circ$
  • B
    $45^\circ$
  • C
    $60^\circ$
  • $90^\circ$
Answer
Correct option: D.
$90^\circ$
Let the required angle be $x$
Now, Sum of linear pair angles $= 180^\circ $
$\Rightarrow x + x = 180^\circ $
$\Rightarrow 2x = 180^\circ $
$\Rightarrow x = 90^\circ $
Hence, the correct answer is option $(d).$
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MCQ 321 Mark
Angles between South and West and South and East are:
  • A
    Vertically opposite angles.
  • Complementary angles.
  • C
    Making a linear pair.
  • D
    Adjacent but not supplementary.
Answer
Correct option: B.
Complementary angles.



From the above figure, we can say that angle between South and West is $90^\circ $ and angle between South and East is $90^\circ .$ So, their sum is $180^\circ .$
Hence, both angles make a linear pair.

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MCQ 331 Mark
In Fig. lines $PQ$ and $ST$ intersect at $O.$ If $\text{POR} = 90^\circ $ and $x : y = 3 : 2,$ then $z$ is equal to:
  • A
    $126^\circ$
  • $144^\circ$
  • C
    $136^\circ$
  • D
    $154^\circ$
Answer
Correct option: B.
$144^\circ$

Since, $\angle\text{POR}, \angle\text{ROT}$ and $\angle\text{TOQ}$ lies on a straight line $POQ,$
then their sum is equal to $180^\circ .$
$\therefore\angle\text{POR}+\angle\text{ROT}+\angle\text{TOQ}=180^\circ$
$\Rightarrow 90^\circ + x + y = 180^\circ $
$\Rightarrow x + y = 180^\circ - 90^\circ $
$\Rightarrow x + y =90^\circ ...(i)$
Also, $x : y = 3 : 2 [$given$]$
Let, $x = 3a$ and $y = 2a$
$\therefore 3a + 2a = 90^\circ [$from Eq$.(i)]$
$\Rightarrow 5a = 90^\circ $
$\Rightarrow \text{a}=\frac{90^\circ}{5}=18^\circ$
Now, $x = 3a = 3 \times 18^\circ = 54^\circ $ and $y = 2a = 2 \times 18^\circ = 36^\circ $
Since, y and z from a liner pair.$\therefore y + z 180^\circ $
$\Rightarrow 36^\circ + \text{z}=180^\circ  \Rightarrow \text{z}=180^\circ-36^\circ [\because\text{y}=36^\circ]$
$\Rightarrow \text{z}=144^\circ$

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MCQ 341 Mark
In Fig. line l intersects two parallel lines $PQ$ and $RS.$ Then, which one of the following is not true$?$
  • A
    $\angle1 = \angle3$
  • B
    $\angle2 =\angle4$
  • C
    $\angle6 = \angle7$
  • $\angle4 = \angle8$
Answer
Correct option: D.
$\angle4 = \angle8$
From the given figure, $PQ || RS$ and l is transversal, Therefore,
$​​​​​​\angle1=\angle3 [$Corresponding angles$]$
$​​​​​​\angle2=\angle4 [$Corresponding angles$]...(i)$
Also, $\angle5=\angle6 [$Vertically opposite angles$]...(ii)$
And $\angle5=\angle7 [$Corresponding angles$]...(iii)$
$​\Rightarrow​​​​​\angle6=\angle7 [$From Eqs.$(ii)$ and $(iii)]$
Also, $\angle2+\angle8=180^\circ [$liner pair$]$
$\Rightarrow​​​​​​\angle4+\angle8=180^\circ$ $​​[\angle2=\angle4]$
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MCQ 351 Mark
If an angle is $60^\circ $ less than two times of its supplement, then the greater angle is:
  • $100^\circ$
  • B
    $80^\circ $
  • C
    $60^\circ $
  • D
    $120$
Answer
Correct option: A.
$100^\circ$
Let the angle be $x,$ then its supplement will be $(180^\circ - x).$
It is given that, the angle $60^\circ $ less than $2$ times of its supplement.
Then, $2(180^\circ - x) - x = 60^\circ $
$\Rightarrow 360^\circ - 2x - x = 60^\circ $
$\Rightarrow 360^\circ - 3x = 60^\circ $
$\Rightarrow 360^\circ - 60^\circ = 3x$
$\Rightarrow 300^\circ = 3x$
$\Rightarrow\text{x}=\frac{300^\circ}{3}$
$\Rightarrow x = 100^\circ $
If $x = 100^\circ ,$ then other angle $= 180^\circ - x = 180^\circ - 100^\circ = 80^\circ $
So, the greater angle is $100^\circ $
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MCQ 361 Mark
What is the measure of complementary angle of $32^\circ ?$
  • A
    $48^\circ$
  • B
    $78^\circ$
  • $58^\circ$
  • D
    $68^\circ$
Answer
Correct option: C.
$58^\circ$
Required Measure of complementary angle $= 90^\circ - 32^\circ = 58^\circ .$
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MCQ 371 Mark
Given a line and a point, not on the line, there is one and only $......$ line which passes through the given point and is $.....$ to the given line.
  • One, parallel
  • B
    One, perpendicular
  • C
    Two, parallel
  • D
    Two, perpendicular
Answer
Correct option: A.
One, parallel
Given a line and a point, not on the line, there is one and only one line.
which passes through the given point and is parallel $($or perpendicular$)$ to the given line.
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MCQ 381 Mark
Two supplementary angles differ by $34^\circ .$ Then the angles are __________.
  • A
    $74^\circ , 107^\circ$
  • $107^\circ , 73^\circ $
  • C
    $120^\circ , 60^\circ $
  • D
    $72^\circ , 108^\circ$
Answer
Correct option: B.
$107^\circ , 73^\circ $
 Let two supplementary angles are $x$ and $y$
We know, $x + y = 180^\circ ....(1)$
As given in the question $x - y = 34^\circ $
$\Rightarrow x = 34 + y .....(2)$
Putting the value of $x$ in terms of $y$ in the eqn $(1)$
we get $34 + y + y = 180$
$\Rightarrow 2y = 146$
$\Rightarrow y = 73^\circ $ And $x = 34 + y = 34 + 73 = 107^\circ $
Therefore, the angles are $107^\circ $ and $73^\circ $
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MCQ 391 Mark
Punita wants to classify a triangle according to the given clue. Two angles of the triangle are complementary. What type of triangle is the one Punita wants to classify$?$
  • Right, because complementary angles add up to $90$ and the difference between $180$ and $90$ is $90.$
  • B
    Obtuse, because complementary angles add up to $45$ and the difference between $180$ and $45$ is $135.$
  • C
    Equiangular, because each of the two complementary angles is equal to $60$ and the difference between $180$ and $120$ is $60.$
  • D
    Acute, because complementary angles add up to $100$ and the difference between $180$ and $100$ is $80.$
Answer
Correct option: A.
Right, because complementary angles add up to $90$ and the difference between $180$ and $90$ is $90.$

 Two angles are Complementary when theyadd up to $90$ degrees.
So, third angle will be $90.$
So, it will be right angle triangle.So Punita wants to classify
$(A)$ Right, because complementary angles add up to $90$ and the difference between $180$ and $90$ is $90.$

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MCQ 401 Mark
In Fig. $\angle\text{AOC}$ and $\angle\text{BOC}$ form a pair of:
  • A
    Vertically opposite angles.
  • B
    Complementary angles.
  • C
    Alternate interior angles.
  • Supplementary angles.
Answer
Correct option: D.
Supplementary angles.
Since, $\angle\text{AOC}$ and $\angle\text{BOC}$ are on the same line $\text{AOB}$ and forming linear pair.
$\therefore \angle \text{AOC}+\angle\text{BOC}=180^\circ$
Hence, $\angle\text{AOC}$ and $\angle \text{AOC}$ are supplementary angles.
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MCQ 411 Mark
The ratio between two complementary angles is $2 : 3$ find the smallest angle.
  • A
    $26$
  • B
    $25$
  • $36$
  • D
    $45$
Answer
Correct option: C.
$36$
Two angles whose sum is $90^\circ $ are said to be complementary.
Given two angles are in the ratio of $2 : 3.$
Let the two angles be $2x$ and $3x.$
So, $2x + 3x = 90^\circ $
$\Rightarrow 5\text{x} = 90^\circ $
$\Rightarrow\text{x}=\frac{90}{5}$
$\Rightarrow\text{x}=18$
Therefore, the two angles are $2x = 36^\circ $ and $3x = 54^\circ $
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MCQ 421 Mark
Two distinct $........$ in a plane cannot have more than one point in common.
  • Lines
  • B
    Points
  • C
    Both lines and points
  • D
    None of these
Answer
Correct option: A.
Lines
If two distinct lines are parallel then they dont have any point in common.
And if two lines are not parallel then they have only one point in common, where they cross each other.
Thus, we can say, two distinct lines in a plane cannot have more than one point in common.
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MCQ 431 Mark
The line which is parallel to $x -$ axis and crosses the curve $\text{y}=\sqrt{\text{x}}$ at an angle of $45^\circ$, is:
  • A
    $\text{x}-\frac{1}{4}$
  • B
    $\text{y}-\frac{1}{4}$
  • $\text{y}-\frac{1}{2}$
  • D
    $\text{y}-1$
Answer
Correct option: C.
$\text{y}-\frac{1}{2}$
Given equation of a line parallel to $x -$ axis is $y = k$
Given equation of the curve is $\text{y}=\sqrt{\text{x}}$
On solving equation of line with the equation of curve, we get $x = k^2$
Thus the intersecting point is $(k^2, k)$
It is given that the line $y = k$ intersect the curve $\text{y}=\sqrt{\text{x}}$
at an angle of $\frac{\pi}{4}$.
This means that the slope of the tangent to $\text{y}=\sqrt{\text{x}}$ at $(k^2, k)$ is tan $\Big(+\frac{\pi}{4}\Big)=\pm1$
$\Rightarrow\Big(\frac{\text{dy}}{\text{dx}}\Big)_{(\text{k}^2-\text{k})}=\pm1$
$\Rightarrow\Big(\frac{1}{2\sqrt{\text{x}}}\Big)_{(\text{k}^2-\text{k})}=\pm1$
$=\text{k}=\pm\frac{1}{2}$
​Thus $\text{y}=\pm\frac{1}{2}$
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MCQ 441 Mark
Find $x;$ if $\angle1=5\text{x}+15^\circ$ and $\angle2=28\text{x},$ angles form linear pair.
  • A
    $40^\circ$
  • B
    $140^\circ $
  • $5^\circ $
  • D
    $20^\circ $
Answer
Correct option: C.
$5^\circ $

 $\angle1+\angle2=180^\circ$ (Linear pair)
$\Rightarrow5\text{x}+15^\circ+28\text{x}=180^\circ$
$\Rightarrow33\text{x}=180^\circ-15=165^\circ$
$\Rightarrow\text{x}=\frac{165^\circ}{33}=5^\circ$

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MCQ 451 Mark
In Fig. $AB || CD$ and $EF$ is a transversal. The value of $y - x$ is:
  • A
    $30$
  • $35$
  • C
    $95$
  • D
    $25$
Answer
Correct option: B.
$35$

Since, $AB || CD$
$\therefore \angle \text{BPQ}=\angle \text{DQF}$ [Corresponding angles]
$\Rightarrow (5\text{x}-20)^\circ=(3\text{x}+40)^\circ$
$\Rightarrow 5\text{x}-20=3\text{x}+40$
$\Rightarrow 2\text{x}=60$
$\Rightarrow \text{x}=30$
$\therefore \text{BPQ}=(5\times 30-20)^\circ=130^\circ$
Now, $\angle \text{APE}=\angle \text{BPQ}$ [Vertically opposite angles]
$\Rightarrow 2\text{y}^\circ=130^\circ$
$\Rightarrow \text{y}=65$
$\therefore \text{y}-\text{x}=65-30$
$=35$
Hence, the correct answer is option $(b).$

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MCQ 461 Mark
If an angle is $28^\circ $ less than its complement, find its measure.
  • $31^\circ$
  • B
    $131^\circ$
  • C
    $28^\circ$
  • D
    $32^\circ$
Answer
Correct option: A.
$31^\circ$

 Two angles are complementary when they add upto form $90$ degrees.
If one angle $= x$
complemen of angle $= 90 - x$
Hence $x = 90 - x -28 ($given$)$
$2x = 90 - 28$
$2x = 62$
$\text{x}=\frac{62}{2}=31$
$= 31$
Hence angle is $31$ and its complementis $59$

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MCQ 471 Mark
The complement of $(90^\circ- a)$ is:
  • A
    $-a$
  • B
    $90^\circ + a$
  • C
    $90^\circ - a$
  • $a$
Answer
Correct option: D.
$a$

Let the complement be $y$ Two angles are complementary if their sum is $90^\circ$
$\therefore 90^\circ - a + y = 90^\circ$
$⇒ y = a$

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MCQ 481 Mark
Find $n ,$ if $\angle\text{A}=11\text{n}-13^\circ$ and $\angle\text{B}=7\text{n}+39^\circ,$ where $A$ and $B$ are vertically opposite angles.
  • A
    $52^\circ$
  • $13^\circ$
  • C
    $130^\circ$
  • D
    $14^\circ$
Answer
Correct option: B.
$13^\circ$

 $\angle\text{A}=\angle\text{B }(\text{Vertically opp. angles})$
$\Rightarrow 11n - 13 = 7n + 39^\circ $
$\Rightarrow 11n - 7n = 39^\circ + 13^\circ $
$\Rightarrow 4n = 52^\circ $
$\Rightarrow n = 13^\circ $

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MCQ 491 Mark
The angle which exceeds its complement by $20^\circ $ is:
  • A
    $45^\circ$
  • $55^\circ$
  • C
    $70^\circ$
  • D
    $110^\circ$
Answer
Correct option: B.
$55^\circ$

 Let the required angle be $x$
Complementary angles $=$ Sum of two angles is $90^\circ $
$\therefore x = (90 - x) + 20$
$x = 90 - x + 202x = 110$
$\therefore x = 55^\circ $

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MCQ 501 Mark
In Fig. the value of $x$ is:
  • $22$
  • B
    $20$
  • C
    $21$
  • D
    $24$
Answer
Correct option: A.
$22$

$ (8x - 41)^\circ + (3x)^\circ + (3x + 10)^\circ + (4x - 5)^\circ = 360^\circ $
$\Rightarrow 8x - 41 + 3x + 3x + 10 + 4x - 5 = 360$
$\Rightarrow 18x - 36 = 360$
$\Rightarrow 18x = 396$
$\Rightarrow x = 22$
Hence, the correct answer is option $(a).$

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