Question

please answer this question,the surface area of a sphere of radius 5cm isfive times the area of csa of a cone of radius r cm.then find the volume of the cone

Answer 1

given 
The SA of a sphere = 5 x The  CSA of a cone
       4 x pi x r^2        =  5 x (2 x pi x r x h)
       4 x 3.14 x 5 x 5 = 5 x 2 x 3.14 x rh
so, 
          radius x height =  4 x 3.14 x 5 x 5
                                        5 x 2 x 3.14
             r  x  h            =  10

suppose if we assume 
      radius of cone = radius of sphere = 5 cm

then, h = 10/5 = 2 cm

    Volume of the cone = 1/3(pi. x r^2 x h)
                                    = 1/3 x 3.14 x 5 x 5 x 2
                                     = 157/3
                                   = 52.33 cm^3