Question: The radii of two circles are 19cm and 9cm respectively. Find the radius of the circle which has a circumference equal to the sum of the circumferences of the two circles.R' = ${56π}/{2π}$ = 28cm.
Solution:
Given, that the radius of the first circle R = 19cm
the radius of the second circle r=9cm
circumference of the first circle = 2πR = 2x π x 19 = 38πcm
circumference of the second circle = 2πr = 2xπx9 = 18πcm
According to the question,
Circumference of the third circle = Circumference of first circle + Circumference of second circle
2πR' = 38π + 18π
R' = 56π/2π = 28cm.