Читать книгу Geometry for Students and Parents - Sergey D Skudaev - Страница 7

If a line drawn from a vertex is perpendicular to the opposite side of the triangle, this line is called an altitude. Altitudes drawn from each angle are concurrent. It means, they intersect in one point.

This point is called orthocenter. A side of the triangle to which an altitude is perpendicular is called a base of the triangle. The area of a triangle equals the product of its base and the altitude, divided by the two. Area=AC * BE/2. See figure 14.

Figure 14. Area of a triangle.