cosec A - 2 2A A = - Vidyadip

MCQ

${\rm{cosec }}A - 2\cot 2A\cos A = $

✓
$2\sin A$
B
$\sec A$
C
$2\cos A\cot A$
D
None of these

✓

Answer

Correct option: A.

$2\sin A$

a
(a) ${\rm{cosec}}\,A - 2\cot 2A\cos A $

$= \frac{1}{{\sin A}} - \frac{{2\cos A\cos 2A}}{{\sin 2A}}$

$ = \frac{1}{{\sin A}} - \frac{{2\cos A\cos 2A}}{{2\sin A\cos A}} $

$= \frac{{1 - \cos 2A}}{{\sin A}} $

$= \frac{{2{{\sin }^2}A}}{{\sin A}}$

$ = 2\sin A$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "MCQ" from 3. trignometrical ratios,functions and identities→3. trignometrical ratios,functions and identities — all question types→MATHS STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

If a circle of radius $R$ passes through the origin $O$ and intersects the coordinate axes at $A$ and $B,$ then the locus of the foot of perpendicular from $O$ on $AB$ is

Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion (A) If 5th and 8th term of a GP be 48 and 384 respectively, then the common ratio of GP is 2.
Reason (R) If 18, x, 14 are in AP, then x = 16.

If ${t_n} = \frac{1}{4}(n + 2)\,(n + 3)$ for $n = 1, 2, 3,……$ then $\frac{1}{{{t_1}}} + \frac{1}{{{t_2}}} + \frac{1}{{{t_3}}} + .... + \frac{1}{{{t_{2003}}}} = $

If two events $A$ and $B$ are such that $P\,(A + B) = \frac{5}{6},$ $P\,(AB) = \frac{1}{3}\,$ and $P\,(\bar A) = \frac{1}{2},$ then the events $A$ and $B$ are

The equation to the sides of a triangle are $x - 3y = 0$, $4x + 3y = 5$ and $3x + y = 0$. The line $3x - 4y = 0$ passes through

$\cot \theta = \sin 2\theta (\theta \ne n\pi $, $n$ is integer), if $\theta = $

If $|8 + z| + |z - 8| = 16$ where $z$ is a complex number, then the point $z$ will lie on

The number of real solutions of real solutions equation $\tan \left( {{e^x}} \right) = {e^x} + {e^{ - x}},\,x > 0,$ is

In an examination,$5$ students have been allotted their seats as per their roll numbers. The number of ways, in which none of the students sits on the allotted seat, is $..........$.

${x^2} + x + 1 + 2k\,({x^2} - x - 1) = 0$is a perfect square for how many values of $k$