Question

For the given diagram, $m\angle ACD=$

• A. $m\angle C+m\angle B$
• B. $m\angle B+m\angle A$
• C. $m\angle C+m\angle A$

Answer 1

The correct option is B $m\angle B+m\angle A$

Here, $\angle ACD$ is an exterior angle for $△ABC$.
$\therefore$ According to the exterior angle theorem:
The exterior angle of a triangle is always equal to the sum of the opposite internal angles.
$\Rightarrow m\angle ACD=m\angle A+m\angle B$