M9 | Maths Made Easy

M9

Question: A cylinder has a radius of 3cm and a length of 8cm. Find its volume, giving your answer to 2 decimal places.

Answer: A cylinder is a “circular prism”. To find its volume, like with any other prism, we just need to multiply the cross-sectional area by the length. Because the cross-section of a cylinder is a circle, we can calculate its area using the formula for the area of a circle: A=\pi r^2.

So in this case, the cross-sectional area is: A=\pi 3^2=28.274…cm^2

Next we just multiply this by the length to get the volume:

V=28.274…\times 8=226.19 cm^3 (2 d.p.)