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

Radius of lower part of cap (r₁) = 10 cm
Radius of upper part of cap (r₂) = 4 cm
Slant height of cap = 15 cm
Area of material used for making it = CSA of frustum + Area of upper part
= π(r₁ + r₂)l + πr₂
= π(10 + 4) × 15 + π × 4²
= 210π + 16π = 226π
= 226 × 22/7 = 710(2/7) cm²
Hence, the area of material used for making is 710(2/7) cm².