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 \(\pi = \frac{22}{7}\)]
- 3.0cm
-
3.5cm
- 7.0cm
- 7.5cm
The correct answer is: B
Explanation
diameter = 12cmradius = \(\frac{12}{2}\)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