MCQ
Suppose $A B C D$ is a trapezium whose sides and height are integers and $A B$ is parallel to $C D$. If the area of $A B C D$ is $12$ and the sides are distinct, then $|A B-C D|$
  • A
    is $2$
  • is $4$
  • C
    is $8$
  • D
    cannot be determined from the data

Answer

Correct option: B.
is $4$
b
(b)

We have,

$A B C D$ is a trapezium.

$A B$ is parallel to $C D$.

Area of trapezium $=12$

$\frac{1}{2} \times h(A B+C D)=12$

$A B+C D=\frac{24}{h}$

Sides and height of trapezium are integer.

$\therefore h$ is a factor of $24$

$h=1,2,3,4,6,8,12,24$

$A B+C D=24,12,8,6,4,3,2,1$

But $A B+C D > h$

$A B+C D=24,12,8,6$

In $\triangle B E C$,

$B E C$ is a right angled triangle.

$\therefore h$ must be $3$ and $4$

When $h=3, B E=4, C E=5$

$A B+C D=8$

$A E+B E+A E=8$

$2 A E=8-B E=8-4$

$A E=2$

$\therefore A B=4+2=6, C D=2$

$\therefore|A B-C D|=|6-2|=4$

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