Ruby, 87 82 77 7774 bytes
->*a{a.map!{|a,b,c|(w=[ac|x,y,z=[a-b,b-c,a-c].map (&:abs).map{|x|xsort;[x/w.sum}.sortz,y/z]}.uniq!=a}
Given the 2 triangles as vectors of 3 complex numbers, calculate length of the three sides as distance between points, sort ascending, then normalize and check if the result isa/b and a/c are the same for both.