**Quote:**

Alternatively state which letter corresponds to the triangle's top vertex.

That is what this question is about. You are given some arbitrary isosceles triangle and some additional information about it. You should figure out on your own which sides/angles are equal (or what are the possible options).

As you can see we easily named the angles with the respective vertices in the explanation. It helped us to comprehend and deal with the information along the way.

Here are the possible options:

Statement (1):

The triangle can be a 45°-90°-45° triangle.

The triangle can be a 72°-36°-72° triangle.

Statement (2) gives way too many options.

When the statements are combined, we are left with a 45°-90°-45° triangle only.