Question

if the difference between circumference and diameter ofa circle is 30cm, then the radius of the circle is

Answer 1

2πr - 2r=30,

2r(π-1) =30,

r×(22/7 -1) =15

r×(22-7)/7 =15,

r×15/7 =15,

then

r=15×7/15,

then

r=7cm