Question:
The radii of two circles are 19 cm and 9 cm, Find the radius of the circle which has circumference equal to the sum of the circumferences of the two circles.
Solution:
Let the radius of the required circle be r.
Now, Circumference of the required circle = Circumference of circle having radius 19 cm + Circumference of circle having radius 9 cm
$\Rightarrow 2 \pi r=2 \pi \times 19+2 \pi \times 9$
$\Rightarrow r=19+9$
$\Rightarrow r=28 \mathrm{~cm}$
Hence, the radius of the required circle is 28 cm.