Answer:

Given, radii of two circles are 15 cm and 18 cm.

We have to find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles.

Circumference of circle = 2πr

Circumference of circle with radius 15 cm = 2π(15)

= 30π

Circumference of circle with radius 18 cm = 2π(18)

= 36π

Sum of circumference of two circles = 30π + 36π

= 66π

Let the required radius of the circle be R.

Circumference of circle with radius R = 2πR

Given, 2πR = 66π

2R = 66

R = 66/2

R = 33 cm

Therefore, the radius of the new circle is 33 cm.

l hope it will help you..

please mark me as brainlist