The GeoVector2D type exposes the following members.
Returns the area of the parallelgram defined by the two vectors. The result will be positive if the sweepdirection from from to to is counterclockwise otherwise it will be negative. If you need the angle of the triangle devide the result by 2.0
Returns the cosine of the angle between the two vectors. Throws an arithmetic exception if any of the vectors is the nullvector.
Returns true, if this vector is exactly the nullvector. Use IsNullVector(GeoVector) if you need more control over precision.
Returns a positive value if the second vector turns to the left relative to the direction of the first vector, a negative value if it turns to the right and 0.0 if the vectors are parallel. The value is the length of the corssproduct of the two vectors in 3D or the area of the paralleogram build by the two vectors.