If a rectangular loaf of bread was cut into slices, the shape and size of each slice would be the same. The loaf is a prism.
A prism has a cross-sectionA shape or surface that is shown as the result of cutting through it in half, so that the inside can be seen, eg a cross-section of a river or of a mathematical shape. which is the same throughout the shape.
A triangular prism has a triangular cross-section.
To calculate the volume of a prism, first calculate the area of the cross-section.
\(\frac{1}{2} \times 2 \times 5 = 5~\text{cm}^2\)
Multiply the area of the cross-section by the length.
\(5 \times 4 = 20~\text{cm}^3\)
\(\text{Volume of a prism} = \text{area of the cross-section} \times \text{length}\)