Question

Let $P$ be an interior point of a triangle $ABC$. Let $Q$ and $R$ be the reflections of $P$ in $AB$ and $AC$, respectively. If $Q,A,R$ are collinear then $\angle A$ equals.

• A. ${30}^o$
• B. ${60}^o$
• C. ${90}^o$
• D. ${120}^o$

Answer 1

The correct option is C ${90}^o$

So from diagram
$\theta +\theta +\varphi +\varphi ={180}^o$
$\angle A=\theta +\varphi ={90}^o$