Chapter 6 of 10All chapters
Chapter 6 of 10
Three dimensions
Volume and surface area.
The common solids
Cuboid volume is length times width times height. A prism is its cross-section area times its length. A cylinder is a prism with a circular cross-section.
- Cone and pyramid are one third of the matching prism.
- Sphere volume is four thirds pi r cubed, surface area is four pi r squared.
Surface area
Surface area is the sum of the faces, so unfolding a solid into a net makes it obvious. Packaging, painting and heat loss all depend on it rather than on volume.