Question 251854
assuming the teepee is cone shaped, then we are dealing with a right triangle with one leg 8 feet and the other is the radius 6 feet
this is a classic 3,4,5 triangle so the hypotenuse is 10 feet
a^2+b^2=c^2
8^2+6^2=c^2 where a=8 and b=6 and c=10
so the support poles need to be over 10 feet to meet and intertwine at the center.
I recommend an additional two feet for the supports
I recommend against using pvc for the supports if a fire is planned in the teepee.
I suspect wooden poles might come out cheaper and stronger than the pvc
and would be more in keeping with the ancestry of the teepee.