The diameter of two cones are equal. If their slant heights be in the ratio of 5 : 4. Find the ratio of their curved surface areas ?
Let their slant height be 5x and 4x.
Given that diameter of two cones are equal
∴ R_{1} = R_{2} = R
S_{1} = πRl = πR(5x)
S_{2} = πRl = πR(4x)
S_{1}/S_{2} = πR(5x)/ πR(4x) = 5/4
S_{1}/S_{2} = 5/4
S_{1} : S_{2} = 5 : 4