What is the length of the vector represented by (1, -1, 1 )^{T} ?

√( 1^{2} + -1^{2} + 1^{2})
= √3

Here are some terms and formulae you may wish to review at length:

- Length of a 2D vector parallel with a coordinate axis.
- Pythagorean Formula.
- Formula for 2D vector length (first version.)
- Formula for 2D vector length (second version.)
- The triangle inequality.
- Formula for 3D vector length.
- Length is always positive or zero.
- Length of the negative of a vector.