Question

Sum of two adjacent angles is 120 degrees. If one angle is 20 degrees, then the measure of other angle is.

• A. 100 degrees
• B. 90 degrees
• C. 45 degrees
• D. 140 degrees

Answer 1

The correct option is A 100 degrees

Given: Sum of the adjacent angles is ${120}^{\circ }$.

Let the required angle be $x$.
$x+{20}^{\circ }={120}^{\circ }$ (Given)
$\Rightarrow x={120}^{\circ }-{20}^{\circ }={100}^{\circ }$
$\Rightarrow x={100}^{\circ }$
So, the required angle measures ${100}^{\circ }$.