I have recently painted my bathroom and wood like to put a trim on the
large bathroom mirror (36" x 30") that is on the wall. I would like
to put a trim around the mirror to make it look more finished. I
picked up moulding like material at Home Depot today. Here is the
problem.. I know that the corners need to meet at a 45degree angle
so that it squares off when finished. Is there an easy way of doing
this? I want to make sure I know what I am doing before I start
cutting. As they say "measure twice, cut once". I would like to
extend that motto to "know what you're doing first". I need help.

Thanks, Al Kondo