Question

a cap is shaped like the frustum of a cone. if its radius on the open side is 10cm and the radius of the upper base is 4cm and its slant height is 15cm, find the area of cloth for making it.

Answer 1

Radius (R) of the upper circular= 4 cm
Radius (r) of the lower circular = 10 cm

so, according to the formula =π(R+r)l + πr^2 =   π(10 + 4) 15 + π(4)2= π(14) 15 + 16π
                                                                 = 210π + 16π = (266x22)/7= 710.28cm^2

Answer 2

=22/7*(10+4)15+22/7*4*4
=352*2*15+352/7
=660+352/7
=660+50.28
=710.28
plz refer to RD sharma page no. 16.75