Question 586372
3.1 (-2, -1)
3.2 -1.5
" What is an auxiliary line presented as in a diagram? Is it a line segment?" is not following the rules. One question per submission. 
See 
http://www.sparknotes.com/math/geometry3/geometricproofs/section3.rhtml
and 
http://www.dummies.com/how-to/content/using-auxiliary-lines-in-proofs.html
and 
http://www.termwiki.com/EN:auxiliary_line
It could be a line or a line segment.