A prism has two congruent parallel polygonal end faces and a uniform cross-section between them. Its volume is \(V=AL\), where \(A\) is the cross-sectional area and \(L\) is the perpendicular separation of the end faces. Think of stacking equal thin layers.
| Solid | Volume |
|---|---|
| Cuboid of length l, width w, height h | \(lwh\) |
| Cube of side s | \(s^3\) |
| Prism of cross-sectional area A and perpendicular length L | \(AL\) |
Example
A triangular prism has a right-triangle cross-section with perpendicular sides 3 cm and 4 cm, and length 10 cm. Its cross-sectional area is \(\dfrac12\times3\times4=6\text{ cm}^2\), so its volume is \(60\text{ cm}^3\).
For an oblique prism, the sloping joining edge is not the perpendicular separation of the bases. The volume formula uses that perpendicular separation.
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