The angle of a sector of a circle of radius 8cm is 240°. This sector
MATHEMATICS
WAEC 1992
The angle of a sector of a circle of radius 8cm is 240°. This sector is bent to form a cone. Find the radius of the base of the cone.
- A. 16/3cm
- B. 15/3cm
- C. 16/5cm
- D. 8/3cm
Correct Answer: A. 16/3cm
Explanation
L = θ/360 x 2πR = 240/360 x 2 x 22/7 x 8/1 ... (1)
This must be equal to the circumference of the circle which is 2πr = 44R/7 .... (2)
equate (1) and (2)
r = 16/3 = 51/3
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