Question

The difference between the circumference and the diameter of a circle is 30cm. Find the diameter of the circle

Answer 1

14 cm

Explanation:

let the radius=r

diameter=2r

circumference=2πr

2πr-2r=30

2r(π-1)=30

`diameter~2r=(30)/(\pi -1) \approx 14 cm`

or

`2r((22)/(7) -1)=30\\2r((22-7)/(7) )=30\\diameter~2r=30 * (7)/(15) =14~cm`