If in the figure below, angle XYZ = 90° and the length of the arc XZ = 10π, then the area of the sector XYZ is

- 10π
- 25π
- 100π
- None of the above

**Solution**

Y is the centre of the circle. Let r be the radius of the circle.

Length of arc XZ = ¼ × 2?r = 10?

r = 20

Arc of sector XYZ = ¼ × ?r^{2} = 100?

The correct option is C.