Question

AOB is straight line. The value of $\angle AOP$ is ___.

• A. ${70}^{\circ }$
• B. ${110}^{\circ }$
• C. ${60}^{\circ }$
• D. ${120}^{\circ }$

Answer 1

The correct option is B

${110}^{\circ }$

Since AOB is straight line,

$\angle AOP+\angle BOP={180}^{\circ }$ (Linear pair)

ie, $x+{20}^{\circ }+x-{20}^{\circ }={180}^{\circ }$

$\Rightarrow 2x={180}^{\circ }$

$\Rightarrow x={90}^{\circ }$

$\therefore \angle AOP=x+{20}^{\circ }=90+20={110}^{\circ }$