Use "def.|def" in a sentence

1. And to do that, I've set up a medial triangle right over here, triangle FED, or actually I should say, triangle DEF, whch is the medial triangle for ABC

삼각형 FED 삼각형 DEF라고 합시다 삼각형 DEF는 삼각형 ABC의 중점을 연결한 중점삼각형입니다