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: 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
