a salesman who's always looking for an 'angle' [=looking for a way to convince people to buy the things he is selling]
The two lines meet at a 30-degree 'angle' to each other. = There is a 30-degree 'angle' between the two lines.
The two lines form a sharp 'angle'. = The two lines meet/intersect at a sharp 'angle' (to each other).
(..) Now... nobody's hurt. - Right? - Right. Nobody hurt. Now, this is the way I'd stab a man who was... taller than I was. Look at the angle. Down and in. And this is the way it was done. Now tell me I'm wrong. - Down and in. There's no argument. - Hold on a minute. Will you give me that? (..)1957 12 Angry Men
(..) It's been bothering me a little, and as long as we're stuck... There was this whole business about the stab wound and how it was made. - The downward angle of it, you know? - Don't start with that again. - They've been over it and over it. - I know, but I don't go along with it. (..)1957 12 Angry Men