I've got three vectors v1[0,1], v2[-1,1], v3[1,1].
I calculated the angles beetween v1-v2 and v1-v3 using the forumla dot(vec1, vec2) / ||vec1|| * ||vec2|| and the both angles are the same (45 degrees).
How to determine that the vector v2 lies on the countercloclwise side (CCW) form v1 (CW angle is 335 degress), and v3 lies on the clockwise (CW) side form v1 (CW angle is 45 degrees).