Question

The sum of the radii of two circles is 10.5 cm and the difference of their circumferences is 13. 2 cm. Find the radii of the two circles. 

Answer 1

The sum of the radii = 10.5 cm

r₁ + r₂ = 10.5 cm .............. (i) 

The difference of circumferences= 13.2 cm 

2 π (r₁ - r₁) = 13.2

(r₁ - r₁) = `13.2/(2 pi)`

(r₁ - r₁) = `(13.2 xx 7)/(2 xx 22)`

r₁ - r₁ = 2.1  ........(ii)

Adding (i) and (ii) 

2r₁ = 12.6 

r₁= 6.3 cm 

Therefore, r₂ = (10.5 - 6.3) cm= 4.2 cm 

Hence, the two radii are 6.3 cm and 4.2 cm