When using the law of sine, why can the ssa case result in zero, one, or two triangles? explain?

Question: When using the law of sine, why can the ssa case result in zero, one, or two triangles? explain? 

As we know that it has happened in the subject of mathematics that when we measure the main angle. So the principal angle is the principal angle in the first quadrant as well as the complement of the second angle that adds to the 180∘ angle in the second quadrant. The two possible angles obtained for A give both possible triangles ABC which make the given ssa completely true.