CHAPTER 10 — Angle between 3D Vectors

We have used the dot product in several calculations:

• Length: Dot product of vector with itself  =  length²
• Perpendicularity: Dot product of perpendicular vectors  =  0
• Angle: cos θ  =   dot product of two unit vectors

This chapter adds nothing new, but extends the third application to the angle between vectors in 3D space.