Question

ABCD is an isosceles trapezoid with DC as one of the bases.

$\angle$ D = (x + 60)${}^{\circ }$

$\angle$ B = (4x)${}^{\circ }$

DC = (x – 3) cm

What is the length of DC?

• A. 27 cm
• B. 24 cm
• C. 21 cm
• D. 18 cm

Answer 1

The correct option is C

21 cm

ABCD is an isosceles trapezium,

In isosceles trapezium sum of opposite angle is 180${}^{\circ }$.

$\angle$ D + $\angle$ B = 180${}^{\circ }$

(x + 60)${}^{\circ }$ + (4x)${}^{\circ }$ = 180${}^{\circ }$

5x = 120${}^{\circ }$

x = 24${}^{\circ }$

So, the length of DC = (24 – 3 ) = 21 cm