Question

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

Answer 1

Let radius of the required circle be r.

Radius of circle A, $r_A=15cm$

Radius of circle B, $r_B=18cm$

Now, $2\pi r=2\pi r_A+2\pi r_B$

$\Rightarrow r=15+18=33cm$