Question 31
Mensuration of SolidsA 120° sector of a circle of radius 21cm is bent to form a cone. What is the base radius of the cone?
- A.3½cm
- B.7cm
- C.10½cm
- D.14cm
- E.21cm
Show the answer and explanation
Answer: B (7cm)
Explanation
The arc becomes the base circumference: 120/360 × 2π × 21 = 2πr, so r = 21/3 = 7 cm.