Question

Two supplementary angles are in ratio $4:5$. Find the measure of greater angle.

• A. ${70}^o$
• B. ${80}^o$
• C. ${100}^o$
• D. ${110}^o$

Answer 1

The correct option is C ${100}^o$

Let two angles be 4x and 5x
Sum of supplementary angles is ${180}^o$
$\therefore 4x+5x={180}^o$
$9x={180}^o$
$x=\frac{180}{9}={20}^o$
So, one angle = $4x=4\times 20={80}^o$
Another angle = $5x=5\times 20={100}^o$
Larger of two angle is ${100}^o$