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

The area of material used is given by :

Area of material   =  Curved surface area of a frustum of cone   +   Area of upper end

$=\ \pi \left ( r_1\ +\ r_2 \right )l\ +\ \pi r^2_2$

$=\ \pi \left ( 10\ +\ 4 \right )15\ +\ \pi \times 4^2$

$=\ \frac{226\times 22}{7}$

$=\ 710.28\ cm^2$

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