Vector math

vectormath.cs

float AngleBetweenVector2(Vector2 vec1, Vector2 vec2)
{
 	Vector2 diference = vec2 - vec1;
	float sign = (vec2.y < vec1.y)? -1.0f : 1.0f;
	return Vector2.Angle(Vector2.right, diference) * sign;
}

float cosAngleBetweenVector3(Vector3 vec1, Vector3, vec2)
{
 float dot = Vector3.Dot(vec1,vec2);
 // Divide the dot by the product of the magnitudes of the vectors
 return dot/(vec1.magnitude*vec2.magnitude);
}