An arc of a circle subtends an angle of 30° on the circumference of a circle of radius 21cm. Find the length of the arc.
-
A.
11cm -
B.
22cm -
C.
44cm -
D.
66cm
Correct Answer: Option B
Explanation
θ = 30 x 2(∠ at center twice ∠ at θ)
∴ θ = 60°
Length of arc = (frac{theta}{360}times 2pi r\
=frac{60}{360}times 2 times frac{22}{7}times frac{21}{1}\
=22cm)