For the proof of BPT theorem, it is said that since a given triangle is obtuse therefore, it ha its altitude external from the triangle. Why is this stated? Which theorem is this?

For the proof of BPT theorem, it is said that since a given triangle i

1.	For the proof of BPT theorem, it is said that since a given triangle is obtuse therefore, it ha its altitude external from the triangle. Why is this stated? Which theorem is this?
Answer» For the proof of BPT theorem, it is said that since a given triangle is obtuse therefore, it ha its altitude external from the triangle. Why is this stated? Which theorem is this?