Triangles in the Coordinate Plane
This Demonstration allows you to manipulate the endpoints of a triangle in a Cartesian coordinate system and finds the perimeter and area of the triangle. The perimeter is found by summing the distances between the endpoints of successive sides and the area is found using Heron's formula.
Heron's formula: If , , and are the side lengths of the triangle, define , the semiperimeter of the triangle. Then the area is given by .