A cylinder is a prism with a circle cross-section, so its volume is πr²h. A cone holds one third of the matching cylinder: volume = ⅓πr²h. A sphere of radius r has volume ⁴⁄₃πr³.
A pyramid also holds one third of the prism with the same base and height: volume = ⅓ × base area × height. Use the radius, not the diameter, and give answers in cubic units, rounded as asked.
Worked example
Find the volume of a cylinder with radius 3 cm and height 10 cm. Give your answer to 1 decimal place.
- Volume = π × 3² × 10 = 90π.
- 90 × 3.14159… = 282.74…
Answer:282.7 cm³
Key words
- cylinder
- a prism with circular ends
- cone
- a circular base narrowing to a point
- sphere
- a perfectly round ball
Practise this
New questions every time.
Common Core-referenced: 8.G.C.9