Question

The radii of two circles are 5cm and 12cm. The area of a third circle is equal to the sum of the area of the two circles. The radius of the third circle is :

• A. 13 cm
• B. 21 cm
• C. 17 cm
• D. 30 cm

Answer 1

Answer:

A. 13 cm

$\pi{r^2}=\pi{\times{5^2}}+\pi{\times{12^2}}$

$r^2= 25 + 144 = 169$

$r = 169 = 13 cm$