A triangle has an area of 24 square centimetres and a base of 8 centimetres. What is its perpendicular height?

Explication

Doubling the area gives 48, the area of the rectangle standing on the same base, and dividing that by the base of 8 leaves a height of 6 cm. Dividing the area by the base without doubling first returns 3 and quietly drops the half that the triangle rule introduced.