posted by Shin .
The quadratic equation x^2−9x+10=0 has roots tanα and tanβ, where 0∘<α+β<180∘. What is the measure of α+β (in degrees)?
x = (9±√41)/2
arctan(x) = 82.6° or 52.4°
Don't know how to evaluate the arctan directly; it appears not to be any familiar angle