Question

If the diameter of the base of a closed right circular cylinder be equal to its height h, then its whole surface area is

(a) $2\pi h^2$ (b) $\frac{3}{2}\pi h^2$

(c) $\frac{4}{3}\pi h^2$ (d) $\pi h^2$

Answer 1

Let diameter of the base of a cylinder (r) = h

Then its height (h) = h

and radius (r) $=\frac{h}{2}$

Whole surface area = $2\pi$ r (h + r)

=$2\pi \frac{h}{2}(h+\frac{h}{2})=2\pi \frac{h}{2}\times \frac{3h}{2}$

=$\frac{3}{2}\pi h^2$

So the correct answer is (b) $\frac{3}{2}\pi h^2$