The perimeter of a sector of a circle of radius 21cm is 64cm. Find the angle of the sector [Take π=227]

A. 70°
B. 60°
C. 55°
D. 42°

Correct Answer: Option B

B. 60°

Explanation

Perimeter of a sector

= 2r + θ/360° x 2 x 22/7 x 21

64 = 2 x 21 + θ/360° x 2 x 22/7 x 21

64 = 42 + θ/360° x 44 x 3

64 – 42 = θ/360° x 11 x 3

22 = 33θ/90

θ=22×30/11

= 60°