This formula is mainly one of the area formulas of triangles. In fact, the area formula of triangle is calculated more. In the plane rectangular coordinate system, the area of a triangle whose three sides are not parallel to the coordinate axis is generally solved by the cut-and-fill method. But sometimes it is more convenient to use the formula of horizontal width and vertical height.

Regional characteristics:

Area is a quantity indicating the degree of a two-dimensional figure or shape or plane layer in a plane. A surface region is a simulation on a two-dimensional surface of a three-dimensional object. Area can be understood as the amount of material with a given thickness, which is necessary to form a shape model, or the amount of paint required to cover a surface with a single coating. It is a two-dimensional simulation of curve length (one-dimensional concept) or solid volume (three-dimensional concept).

The area of a shape can be measured by comparing a fixed size shape with a square. In the International System of Units (SI), the standard unit area is square meters. A square area with an area of one meter and an area of three square meters will have the same shape as three such squares. In mathematics, the unit square is defined as 1, and the area of any other shape or surface is a dimensionless real number.