Triangle ABC is an isosceles right triangle with a right angle at A. Segments BD and BE trisect angle ABC. What is the degree measure of angle BEA?
Because the triangle is isosceles we know that $\angle{ABC} = 45$ ($\frac{180-90}{2}$)
Because it trisects angle $ABC$, we know that $\angle{EBA} = 15$. Thus, we subtract $180 - 15 - 90 = 75$, because $EAB$ is a triangle.
Therefore, our answer is $\boxed{75}$.