Question 18
Mensuration of Plane ShapesIn the diagram below, O is the centre of the two concentric circles of radii 13cm and 10cm respectively. Find the area of the shaded portion in the sector with an angle of 120° at the centre.
- A.1/3πcm2
- B.πcm2
- C.3πcm2
- D.23πcm2
- E.46πcm2.
Show the answer and explanation
Answer: D (23πcm2)
Explanation
Shaded area = 120/360 × π(132 − 102) = 1/3 × 69π = 23π cm2.