And the distance between and the line segment

I.2 INTERSECTION OF LINE SEGMENTS

• For further efficiency, the cases of r1, r2, r3, or r4being 0 can be handled separately. In these situations, one of the end points is the point of intersection, and need not actually be computed

I.3 DISTANCE FROM A POINT TO A LINE

1
2|AxBy + BxPy + PxAy – AyBx – ByPx – PyAx|.

Rearranging terms to save multiplies gives the following formula for a2, twice the signed area of �ABP: