Question

The radius of a circle of circumference equal to the sum of circumference of two circles of diameter 36 cm and 20 cm will be :

(A) 56 cm

(B) 42 cm

(C) 28 cm

(D) 16 cm

Answer 1

Answer is (C) 28 cm

Diameters of two circles are 36 cm and 20 cm respectively so their radius r₁ = \(\frac { 36 }{ 2 }\) = 18 cm and r₂ = \(\frac { 20 }{ 2 }\) = 10 cm

Let R be the radius of required circle.

According to the question

Sum of circumference of given circles = Circumference of required circle