Question 1058557
Let x represent the measure of one of the base angles. The other 
base angle is also represented by x.


Since the vertex angle is twice the base angle, this angle is represented
by 2x.


The sum of the three angles must be 180 degrees:


x + x + 2x = 180


4x = 180


x = 45


Thus, each of the base angles is 45 degrees, and the vertex angle is
2(45) = 90.


The triangle must be a 45-45-90 right triangle then.