Given the coordinates of the three vertices of a triangle ABC, the area can be found by the formula below.

When the coordinates of the three vertices A,B,C of any triangle are given as A(Ax, Ay), B(Bx, By) , C(Cx, Cy) the area of the triangle is given by:

Area = (A x ( B y − C y ) + B x ( C y – A y ) + C x ( A y – B y ) ) / 2

where A_{x} and A_{y} are the x and y coordinates of the point A

Even if the coordinates of the triangle are negative, this formula can be used to calculate the area.

Polygons can never have a negative area. It can only have absolute value. This means that it is always positive even if the formula produced a negative result.