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.

**Solution:**

Radius on the open side of the frustum of a cone **cm**

Radius at the upper base **cm**

Slant height **cm**

**Area of the material used for making cap = curved surface area + Area of the upper base**