When doing proofs, can I name an angle angle 1 if it is not given in the diagram?

Question

I'm trying to proof lines are perpendicular in my proof.  I'm setting it up as a two column proof, but no angles are named, can I name the angles in my diagram and then reference that angle in my proof?

Answer 1

Jennifer,

Usually in your proof, and so that others can understand what you've done without looking at your picture, you will use the points to name angles.  But, as long as you make it specific that you are naming this particular angle to be angle 1, and mark it on your picture, it should be fine, as long as your teacher has not forbidden it.  But, be careful what angle you mean when you do this renaming.