Question

The formula for the circumference of a circle is C = 2πr . If a circle has circumference C = 24 , what is the radius of the circle?

Answer 1

The circumference of the circle = C = 2πr = 24 cm,

Where, r = √x+2

Or, 2π(√x+2) = 24

Or, (√x+2) = 24/2π = 24/2×22/7 = 24×7/44 = 3.82

Or, (√x+2) = 3.82

Squaring both sides,

(√x+2)² = (3.82)²

Or, x+2 = 14.59

Or, x = 14.59 - 2

Or, x = 12.59 cm

And r = √x+2 = √12.59+2 = √14.59 = 3.82 cm

Therefore, x = 12.59 cm and radius = r = 3.82 cm