height. Alternatively, multiply the base length by the perpendicular height and then halve to find the area of a triangle. The base and the perpendicular height are at right angles to each other.

A triangle is a closed shape with three sides and three vertices. The general formula to calculate the area of a triangle is half of the product of its base and height.

A KS3 Bitesize 11-14 Maths guide showing you how to prove the area of a triangle is half base × height.

Along the top line (height) of the triangle, the student has written 3.75, while the vertical line (base) is indicated as 1.875. These values mean the area of the triangle should be 3.5156.