Question

A right circular cylinder has a height of 10 in. and a radius two-fifths it's height.The exact surface area of the cylinder is ___ π in^2.

Answer 1

Given a right circular cylinder with a height of 10 in.

For a circular cylinder, a curve surface area will be used

$\begin{gathered} C\mathrm{}S\mathrm{}A\text{ = 2}\pi rh \\ \text{Height = 10in , radius = }\frac{2}{5}\text{ h = }\frac{2}{5}\text{ x 10 = 4in} \\ C\mathrm{}S\mathrm{}A\text{ = 2 }\pi\text{ x 4 in x 10 in} \\ C\mathrm{}S\mathrm{}A\text{ = 80 }\pi in^2 \end{gathered}$

Hence the exact surface area of the cylinder = 80 π in²