Question

Three angles of a quadrilateral are equal and the measure of the fourth angle is ${120}^{\circ }$. Find the measure of each of the equal angles.

Answer 1

Sum of $4$ angles of a quadrilateral ${360}^{\circ }$
One angles = ${120}^{\circ }$
$\therefore$ Sum of other three angles $={360}^{\circ }-{120}^{\circ }={240}^{\circ }$
But each of these $3$ angles are equal
$\therefore$ Each of equal angles = $\frac{{240}^{\circ }}{3}={80}^{\circ }$