I have to solve a math problem written in English. The wording is the following :
" In triangle ABC, the angle bisector of angle A intersects line BC at D and the circumference of triangle ABC at E. The external angle-bisector of angle A intersects line BC at F and the circumference of triangle ABC at G. Prove that DG⊥EF. "
I am quite confused regarding the meaning of "circumference". How could an angle bisector intersect the circumference of a triangle?!
So, I am wondering this because I have read that perimeter was a synonym..
Could you please enlighten me? Thanks!