The area of parallelogram is base * height. A parallelogram formed by inverting two identical triangles, whose base and height are equal to those of the triangle.

Calculate the area of the parallelogram and divide it by 2. (Because it is composed of two identical triangles)

If S is used to represent the area of the triangle, and α and H are used to represent the base and height of the triangle respectively, then the area formula of the triangle is expressed in letters as S=ah÷2.