The angle of a sector of a circle of radius 8cm is 240^\circ. 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
E
16/10cm
Verified Correct Answer: A.
Step-by-Step Mathematical Solution
L = \theta/360 x 2\piR = 240/360 x 2 x 22/7 x 8/1 ... (1)
This must be equal to the circumference of the circle which is 2\pir = 44R/7 .... (2)
equate (1) and (2)
r = 16/3 = 5\(\frac{1}{3}\)
Source: Myschool Past Questions Archive (Record #23152)