What's the best way to draw two planes intersecting at an angle that isn't $\pi /2$?
If I make them both vertical and vary the angle between them, the diagram always looks as though our viewpoint has changed but the planes are still intersecting at $\pi /2$.
I can't quite work out how to draw one or both of them non-vertical in such a way as to make the angle between them appear to be obviously not a right angle.
Thanks for any help with this!