# Projection matrix onto a subspace

1. Oct 22, 2008

### cheertcc101

Alright so I am trying to find the projection matrix for the subspace spanned by the vectors

[1] and [2]
[-1] [0]
[1] [1]

I actually have the solution to the problem, it is ...

P = [ 5 1 2 ]
(1/6) [1 5 -2]
[2 -2 2]

Every formula I have found is not for two vectors but a vector and a matrix or something else. I found the formula P = A(ATA)-1AT but that makes no sense for what A could be since I'm given two vectors and not a matrix. I feel like I'm missing something simple.