Question

Two circles touch internally the sum of their areas is 165 cm square and the distance between the centre is 4 cm the radius of the circle find

Answer 1

Answer:

Radius of Ist.circle=R

... 2nd..... =r

πR^2+πr ^2 = π(R2 + r2) =165

R2 + r2=165/π =165 / 3. 14=52.5cm

R-r = 4cm. . (i)

(R-r)^2 = R^2-2Rr+ r^2

4^2 = 52.5-2Rr

2Rr=52.5-16 = 36.5

(R+r)^2 = R^2+2 Rr+r^2

... = 52.5+36.5=89

R+r=v89=9.4cm. (2)

solve eqn (1)&(2)

R=6.7cm and r=2.7cm Ans