Chapter-12. Areas Related to Circles Mathematics class 10 in english Medium CBSE Notes

Q1. Two circles touch internally, the sum of their areas is 116 π. Distance between their center is 6 cm. Find the radii of circles. 

Solution: 

Let the radius of small circle = r cm. 

Then the radius of Large circle R = 6 + r cm. 

Sum of their areas = 116π cm 

πR² + πr² = 116 π cm 

π(R²+ r²) = 116π

R²+ r² = 116

(6 + r)² + r² = 116

36 + r² + 12r + r² = 116

2r² + 12r + 36 = 116