Question

In a triangle ABC, $\angle B={50}^o$ and $\angle A={60}^o$. Suppose BC is extended to D. Find $\angle ACD.$

Answer 1

In $△ABC$,

$\angle ACD$ is exterior angle for a $△ABC$ with refrerence to angle $A$ and angle $B$

As we know that exterior angle is sum of interior opposite angles.

$\therefore \angle ACD=\angle B+\angle A$

$\Rightarrow \angle ACD={50}^o+{60}^o$

$\Rightarrow \angle ACD={110}^o$