Newbie: How draw an angled line ending where it cross a line

[Sudan]

I have drawn a square (snapped to grid) of 5" by 5". I want to a drawn an angled line through the square.

Start point of angled line is at the 0,0 (lower left) corner of the square. The angle of the line is to be 67.5 degrees. The end point of the line is to be on the top of the square (i.e., the line of the square defined as the line segment 0,5 to 5,5).

I know I could calculate the length of the line and where on the top of the square the angled line should end. But it seems to me there should be a way of automatically doing this. I.e., telling the QCad program to place the end of the angled line where it crosses (is the term "bi-sect"?) the top line of the square.

I'm just staring using CAD and I have no experience drafting (I don't know technical terminology), so an explanation is appreciated it. Thanks.