Question

The complement of an angle which is two-fifths of ${90}^{\circ }$ is ___.

• A. ${90}^{\circ }$
• B.

  ${54}^{\circ }$

• C.

  ${24}^{\circ }$

• D.

  ${36}^{\circ }$

Answer 1

The correct option is B

${54}^{\circ }$

Given that angle is two-fifth of ${90}^{\circ }$. Let that angle be $x$ and its compliment be $y$.

$\Rightarrow x=\frac{2}{5}\times {90}^{\circ }=2\times {18}^{\circ }={36}^{\circ }$

Two angles are said to be complimentary if sum of those two angles is ${90}^{\circ }$.
$\Rightarrow x+y={90}^{\circ }$

$\Rightarrow {36}^{\circ }+y={90}^{\circ }$

$\Rightarrow y={54}^{\circ }$