Question

If the lateral area of a right circular cylinder is 90 cm2 and its volume is 225 cm3, find its radius.

Answer 1

Area of right circular cylinder is $A= 2\pi r h$ and volume is $V= \pi r^2 h$ . Thus we have

$$2\pi rh= 90 \\ rh =\cfrac{45}{\pi}......Eq[1]\\ r^2 h=\cfrac{225}{\pi}.......Eq[2]$$

Now dividing Eq[2] by Eq[1]...

$$r=\cfrac{225}{45}\\ r= 5cm.....Ans$$

radius of right circular cylinder is 5 cm.