Question

The total surface area of a cylinder is 8448 sq cm. If the radius of its base is 28 cm, what is its height?

Answer 1

Radius of cylinder (r) = 28cm
Height of cylinder (h) =?
Total surface area of cylinder = 8448 sq cm
Suppose the height of the cylinder is h cm.
Total surface area of cylinder = 2πr(r + h)
$$\begin{gathered} \Rightarrow 8448=2\times \frac{22}{7}\times 28\left(28+h\right) \\ \Rightarrow 28+h=\frac{8448\times 7}{2\times 22\times 28} \\ \Rightarrow 28+h=48 \\ \Rightarrow h=48-28 \\ \Rightarrow h=20cm \end{gathered}$$