/// <summary>
/// Assumes the two lines u1-v1 and u2-v2 are not parallel.
/// </summary>
public static VecRat2 LineIntersection(VecRat2 a1, VecRat2 b1, VecRat2 a2, VecRat2 b2)
{
Rational s1det = MathAid.Det2(a1, b1);
Rational s2det = MathAid.Det2(a2, b2);
VecRat2 diff1 = a1 - b1;
VecRat2 diff2 = a2 - b2;
return((s1det * diff2 - s2det * diff1) / MathAid.Det2(diff1, diff2));
}
public static Rational TriangleTwiceSignedArea(VecRat2 a, VecRat2 b, VecRat2 c)
{
return(MathAid.Det2(b - a, c - a));
}