Question

Question 1
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.

Answer 1

Let the radius of a circle be r.

$\therefore$ Circumference of a circle $=2\pi r$

Let the radii of two circles are $r_1$ and $r_2$ whose values are 15 cm and 18 cm, respectively .

$\Rightarrow$ $r_1=15cm,r_2=18cm$

Now, by given condition,

Circumference of circle = Circumference of first circle + Circumference of second circle

$\Rightarrow 2\pi r=2\pi r_1+2\pi r_2$

$\Rightarrow r=r_1+r_2$

$\Rightarrow r=15+18$

$\therefore r=33cm$

Hence, required radius of a circle is 33 cm.