In trapezium $ABCD$, $AB \parallel CD$. If $\angle A = 3 \angle D$, then $\angle A$ equals:

Question

Aicharya · Accepted Answer

$\angle A$ and $\angle D$ are co-interior angles between the parallels $AB$ and $CD$, so $\angle A + \angle D = 180^{\circ}$. With $\angle A = 3\angle D$: $4\angle D = 180 \Rightarrow \angle D = 45^{\circ}, \angle A = 135^{\circ}$.

In trapezium $ABCD$, $AB \parallel CD$. If $\angle A = 3 \angle D$, then $\angle A$ equals:

Solution