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.

Explanation

To find the area of material used for making the fez, which is shaped like the frustum of a cone, we need to calculate the curved surface area and the area of the upper circular base. Here are the steps to solve the problem:

### Step 1: Identify the dimensions
- The radius of the lower base (larger radius, r2) = 10 cm
- The radius of the upper base (smaller radius, r1) = 4 cm
- The slant height (l) = 15 cm

### Step 2: Calculate the curved surface area (CSA) of the frustum
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