Question

Find the ratio between the radius and slamt height of a cone by rolling up a sector with its central angle 120. If the curved surface area of a cone is 108 pi sq cm. Find the radius and slant height of the cone?

Answer 1

Curved surface area of cone = πrl

πrl = 108 × 22/7

πrl = 339.4285714

Now Area of sector formed = CSA of cone

theta/ 360 ×πr^2 = πrl

120/360 × 22/7 ×r^2 = 339.4285714

r^2 = 324

r = 18 ------> 1

Now put the value of r in

rl = 108

18 ×l = 108

l = 6 -----> 2

so the ratio of radius is to slant height that is r : l = 3 : 1.