Find the radius of a circle whose circumference is equal to the sum of the circumference of two circles of radii 15 cm and 18 cm .

Explanation

Let the radius of a circle be r.
`:.` Circumference of a circle = `2pir`
Let the radii of two circles are `r_(1) and r_(2)` whose values are 15 cm and 18 cm respectively.
i.e., `r_(1) ` = 15 cm and `r_(2)` = 18 cm
Now, by given condition ,
Circumference of circle= Circumference of first circle + Circumfernce of second circle
`rArr 2pir = 2pir_(1) + r_(2)`
`rArr r = r_(1) + r_(2)`
`rArr r= 15 + 18`
`:.` r = 33cm
Hence, required radius of a circle is 33 cm .