# Thornton & Marion, Classical Dynamics of Particles and Systems, 5th Edition

## Chapter 1. Matrices, Vectors, and Vector Calculus

### Problem 19. Vector Algebra

#### The problem asks you to derive

- Angle transformation formulae using vector algebra.

#### You should know about

- The basic concept of a vector algebra
- Law of cosines
- Pythagorean trigonometric identity

#### Solution

#### References

https://en.wikipedia.org/wiki/Law_of_cosines

https://en.wikipedia.org/wiki/Pythagorean_trigonometric_identity