Question

In the figure shown above, the radius $OA$ is equal to the chord $AB$. Then, what is $\angle APB$?

• A. ${30}^{\circ }$
• B. ${60}^{\circ }$
• C. ${15}^{\circ }$
• D. ${45}^{\circ }$

Answer 1

The correct option is A ${30}^{\circ }$

$OAB$ is an equilateral triangle(all sides are equal). So $\angle AOB={60}^{\circ }$
$\Rightarrow \angle APB=\frac{1}{2}\angle AOB={60}^{\circ }÷2={30}^{\circ }$.