Question

The measure of angle subtended by a diameter in a semicircle is

• A.
  ${60}^{\circ }$
• B.
  ${90}^{\circ }$
• C.
  ${45}^{\circ }$
• D.
  ${180}^{\circ }$

Answer 1

The correct option is B

${90}^{\circ }$
The angle subtended by an arc of a circle at the centre is double the angle subtended by it at any point on the remaining part of the circle.

$\therefore \angle AOB=2\angle APB\Rightarrow {180}^{\circ }=2\angle APB\Rightarrow \angle APB={90}^{\circ }$

Hence, the correct answer is option (b).