Angle between two Vectors 2D

Question

I\'m trying to compute the angle between two vectors. I tried this, but it always returns zero:

public double GetAngle(Vector2 a, Vector2 b)
{
double angle = Mat         


        

Answer 1

tan(angle) = opposite/adjascent

arctan(opposite/adjascent) = angle

opposite = a.y - b.y

adjascent = b.x - a.x

Math.Atan((a.Y - b.Y) / (b.X - a.X));