Question

A cone shaped object, resting on the ground and having a radius of 7 cm, is to be covered with a canvas of 2 cm wide. Find the cost of the canvas used to cover the same object of slant height 20 cm, if the price is Rs.10 per metre

Answer 1

The radius of cone=r= 7cm

And slant height=l=20 cm

so curved surface area of cone=πrl=$\frac{22}{7}$ ×7×20 =440 cm²

To cover that cone a canvas needed,whose width=2 cm

So the length of canvas will be=$\frac{440}{2}$ = 220 cm=2.20 meters

Price of 1 mtr canvas=10/-

So price of 2.20 meters canvas will be=2.20×10=22/- (Answer)