What is the radius of a circle if the difference between the circumference and diameter of the circle is 30cm?

Answer 1

Circumference = 2 pi r

diameter = 2 r

Circumference - diameter = 30 cm

2 pi r - 2 r = 30

2(pi r - r) = 30

pi r - r = 15

r(pi - 1) = 15

r = 15/(pi-1) cm