The area of a sector a circle with diameter 12cm is 66cm2. If the sector is folded to form a cone, calculate the radius of the base of the cone [Take (pi = frac{22}{7})]
-
A.
3.0cm -
B.
3.5cm -
C.
7.0cm -
D.
7.5cm
Correct Answer: Option B
Explanation
diameter = 12cm
radius = (frac{12}{2})cm = 6cm
area of sector = 66cm2
area of sector = area of cone
66 = (pi rl)
66 = (frac{22}{7} times r times 6)
divide both sides by 6
11 = (frac{22}{7}r)
22r = 11 x 7
r = (frac{77}{22})
= 3.5cm