Hi there. I must give the eigenvalues and the eigenvectors for the matrix transformation of the orthogonal projection over the plane XY on
So, at first I thought it should be the eigenvalue 1, and the eigenvectors (1,0,0) and (0,1,0), because they don't change. But I also tried doing the calculus, and then I've confused.
From the characteristic polynomial I get to:
Then, I have as eigenvalues 0, and 1 twice.
I get to:
and then the eigenvector:
So I thought, shouldn't it be zero? because of the projection. I have doubts with this, but I know that as it is a symmetrical matrix it should be diagonalizable, and then I should get a basis from the eigenvectors, which I wouldn't find with just the first reasoning, and then I need a linear independent vector, like this one, respect to the first I gave.
And then for :
Which gives: , and implies: , I think that have sense.
Well, I need some help with this. Can anybody tell me if this is right, and if it isn't, what I did wrong?
PS: I have my final exam tomorrow :P