Question

A wooden article was made by scooping out a hemisphere from each end of a cylinder, as shown in the figure. If the height of the cylinder is $20cm$ and its base is of diameter $7cm$, find the total surface area of the article when it is ready.

Answer 1

Height of the cylinder $=20cm$
Base radius of the cylinder $=3.5cm$

The total surface area would be the sum of the curved surface area of cylinder and the surface areas of 2 hemispheres which is given by
$2\pi rh+2\times 2\pi r^2=2\pi rh+4\pi r^2=2\pi r(h+2r)=2\times \frac{22}{7}\times 3.5\times (20+2\times 3.5)=22\times 27=594c{m}^2$