This depends crucially on the condition . Notice that if the length BC is less than BA then the triangles XYZ and XYZ' in this picture would both have the same SSA data as ABC (where YZ'=YZ=BC), although XYZ' is not congruent to ABC:
That is a typical SSA situation, where the position of Z is ambiguous.
But if then the position of Z' would be to the left of X and the triangle XYZ would look like this:
Notice that in the triangle XYZ' the angle at X is now the supplement of what it is in the triangle XYZ. So the triangle XYZ' does not have the same SSA data as ABC in this case.
I think that is why the question asks for an "SsA" proof, with the second s in lower case. It's essential that the side AB should be shorter than BC.