Is triangle congruence SAS an axiom? I was wondering if there is a way to prove SAS in triangle congruence with Euclidean axioms.
Thank you for your help! 

This research paper talks about this:
http://www.iosrjournals.org/iosr-jm/papers/Vol10-issue1/Version-3/D010132633.pdf
To sum it up: it is a theorem.

This  research  has  shown  that  the  elusive  SAS  (side  angle
side)  theorem  of  congruence  of  triangles  can be  proved
analytically.  Indeed  same  goes  for  the  other  congruence
theorems  of  triangles  by  applying,  mutatis mutandis,  the  data
for  each  theorem  on  the  cross  section  of  a  double  cone  with
the  appropriate  construction.

