What are 3 skills you should know before starting geometry?

cassie: What are 3 skills you should know before starting geometry?
I have a group project to do and I need 3 skills you should know and be able to do before starting geometry. Mostly algebra skills I’m guessing..

Examples:
-Factoring trinomials
-Pythagorean Theorem

I need more!

Answers and Views:

Answer by F. Alex !!
first of all..: is Algebra.