In rhombus $ABCD$, $\angle A = 60^{\circ}$. Then $\angle B$ equals:

In rhombus $ABCD$, $\angle A = 60^{\circ}$. Then $\angle B$ equals:
  1. $60^{\circ}$
  2. $90^{\circ}$
  3. $120^{\circ}$
  4. $150^{\circ}$

Solution

A rhombus is a parallelogram, so adjacent angles are supplementary. $\angle B = 180 - 60 = 120^{\circ}$.

Asked in: IMO

Practice more UNDERSTANDING QUADRILATERALS questions on Aicharya