Question

Find the angle which is double of its supplement.

Answer 1

Two angles are said to be supplementary angle if sum of their measures is $180°$.

Let the angle be $x$

Then, the angle double of supplement angle $x$ is $2x$

Then,

$$\begin{gathered} \angle x+2\angle x=180° \\ \Rightarrow 3\angle x=180° \\ \Rightarrow \angle x=\frac{180°}{3}=60° \end{gathered}$$

$2\angle x=2\times 60°=120°$

Hence, the angle double of its supplement is $120°$.