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.

Area of Triangle Formula Area of a triangle is half the product of its base and height. Therefore, to calculate the area of a triangle, one should have its base and height measurements.

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.