Question

A fez, the cap used by the Turks, is shaped like the frustum of a cone (see the figure).

If its radius on the open side is 10 cm, radius at the upper base is 4. cm, and its slant height is 15 cm, find the area of material used for making it.

Answer 1

Radius on the open side of the cap, R = 10 cm. 

Radius of upper end, r = 4 cm. 

Slant height l = 15 cm

R = 10 cm, r = 4 cm, l = 15 cm 

∴ Curved surface = π × l × (R + r) 

= π × 15 × (10 + 4) 

= \(\frac{22}{7}\) × 15 × 14 = 660 cm² 

∴ Area of cap at the end

∴ Area of material used for making it,