Question

The measure of an angle is twice the measure of its supplementary angle. Find its measure.

Answer 1

Let the required angle = x
$\therefore$ Its supplementary angle = ${180}^{\circ }-x$
$\therefore x=2({180}^{\circ }-x)={360}^{\circ }-2x\Rightarrow x+2x={360}^{\circ }\Rightarrow 3x={360}^{\circ }\Rightarrow x=\frac{{360}^{\circ }}{3}={120}^{\circ }$
$\therefore$ Required angle = ${120}^{\circ }$