Question

Find the radius of a circle whose area is equal to the sum of the areas of 2 circles of radii 12 cm and 5 cm

Answer 1

Answer

π has been taken common

Answer 2

Area of circle = Sum of areas of two small circles =
$\pi ( 12 ^{2} + 5 {}^{2} ) = 169\pi$
Area of the circle =
$\pi r ^{2}$
Thus
$\pi \: r { }^{2} = 169\pi$
Therefore, r^2 = 169
r = 13 cm