Hey

I'm stuck at a question here and I am not really sure how to go about it. If someone could give me some guidance I would appreciate it.

Okay so here's the question:

Calculate the matrix if A is the matrix for the representation/image that is the orthogonal projection on the plane .

Sorry if my translation is a bit confusing. If it is I could try and clarify but for a better lack of words this is what I got out from it. What I need is to find out the value of matrix A. If I get that I am sure I can solve it on my own.

Thanks in advance!