Question

A rocket is in the form of a circular cylinder closed at the lower end and a cone of the same radius is attached to the top. The radius of the cylinder is 2.5 m, its height is 21 m and the slant height of the cone is 8 m. Calculate the total surface area of the rocket.

Answer 1

Radius of the cylinder = 2.5 m
Height of the cylinder = 21 m

Curved surface area of the cylinder $=2\mathrm{\pi rh}=2\times \frac{22}{7}\times 2.5\times 21=330{\mathrm{m}}^2$
Radius of the cone = 2.5 m
Slant height of the cone = 8 m
Curved surface area of the cone$=\mathrm{\pi rl}=\frac{22}{7}\times 2.5\times 8=62.86{\mathrm{m}}^2$

Area of circular base$={\mathrm{\pi r}}^2=\frac{22}{7}\times 2.5\times 2.5=19.643{\mathrm{m}}^2$
∴ Total surface area of rocket$=330+62.86+19.643=412.503m^2$