I've got a question regarding transformation matrices, following statement:
Let $f: \mathbb{R^3} \rightarrow \mathbb{R^3}$ be orthogonal projection on the line $l:t(1,1,1), t \in \mathbb{R}$ and let $A$ be its transformations matrix. Then rank(A) is less than nulldimension(A), for which the examiner says its true.
I don't really understand how i'm supposed to find out the answer. This is a question where we will only answer true/false, which means you should be able to draw your conclusions from theory, which I'm not able to do.
Thanks!