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

Cylindrical portion:

Radius, r = 2.5 m

Height, h = 21 m

Surface area $=2\pi rh=2\times \frac{22}{7}\times 2.5\times 21=330m^2$

Conical portion:

Radius, r = 2.5 m

Slant height, l = 8 m

Curved surface area $=\pi rl=\frac{22}{7}\times 2.5\times 8=62.86m^2$

Circular top:

Radius = 2.5 m

Area $=\pi r^2=\frac{22}{7}\times {2.5}^2=19.64m^2$

Total surface area of the rocket $=330+62.86+19.64=412.5m^2$