Question

In the trapezium ABCD shown below, if $\angle ADC={120}^{\circ }$, then find the measure (in degrees) of $\angle DCB$.

• A. 60

Answer 1

The correct option is A 60

Given: ABCD is a trapezium.

$\Rightarrow BC\parallel AD$

$\Rightarrow \angle ADC+\angle DCB={180}^{\circ }(\text{Interior angles on the same side of}$
$\text{transversal DC})$

$\Rightarrow {120}^{\circ }+\angle DCB={180}^{\circ }$

$\Rightarrow \angle DCB={180}^{\circ }-{120}^{\circ }$

$\Rightarrow \angle DCB={60}^{\circ }$