created 08/26/97; revised 08/12/00; 07/23/03; 07/23/09; 01/15/15

This chapter discusses two important facts:
**(1)** The dot product
of a column matrix with itself returns
the square of the
length of the vector it represents.
**(2)** The dot product of two column matrices that represent
orthogonal vectors is zero.

- The dot product and vector length
- Unit vectors
- Unit normal
- Dot products of orthogonal vectors and of their column matrices
- How to construct a vector orthogonal to a given vector

Let **v** = ( 3, 4 )^{T}

**v · v**= ?- The length of
**v**= ?