The sum of the radii of two circles is 140cm and difference of their circumference is 88cm. Find the diameter of the circles.
Let the radii be r1 & r2
Then r1+r2=140cm ……….(1)
c1−c2=88cm
⇒2πr1−2πr2=88cm
⇒2π(r1−r2)=88
r1−r2=44/π=14cm …………(2)
Adding equation (1) & (2)
⇒2r1=154cm
r1=77cm
Subtracting equation (1) & (2)
2r2=126
r2=63cm.