Question

What is the measure of complementary angle of ${20}^{\circ }$?
(1) ${60}^{\circ }$
(2) ${70}^{\circ }$
(3) ${80}^{\circ }$.

Answer 1

We know, two angles are complementary when they add up to ${90}^o.$

Given, measure of one complementary angle is ${20}^o.$

$\Rightarrow$ Measure of other complementary angle $={90}^o-{20}^o$ $={70}^o.$

$\therefore$ Measure of a complementary angle of ${20}^o={70}^o$.

Therefore, $\left(2\right)$ ${70}^o$ is correct.