Answer:
they are always similar because if the vertex of one is congruent to the vertex angle of another.
Step-by-step explanation:
let the congruent vertex angles have measure x. in any triangle the three angles have to add up to 180 so the base angle has to add up to 180-x in both triangles. in a isosceles triangle the base angles are congruent so each base angle has to measure (180-x)/2 in both triangles. therefore all three angle of the 2 triangles are congruent so the triangles must be similar by AA.
