Question

Find the measure of $\angle ABC$ in the figure below:

• A. ${55}^{\circ }$
• B. ${45}^{\circ }$
• C. ${35}^{\circ }$
• D. ${25}^{\circ }$

Answer 1

The correct option is B ${45}^{\circ }$

According to the exterior angle property, $\angle ACD=\angle ABC+\angle BAC$

$\Rightarrow \angle ABC=\angle ACD-\angle BAC$
$={100}^{\circ }-{55}^{\circ }$
$={45}^{\circ }$
$\therefore$ the measure of $\angle ABC$ is ${45}^{\circ }.$