umm...you don't have a lot of options here. combine the fractions in the numerator and denominator and simplify (note: you may need to conjugate). for the record, i used a different formula and got the answer, it's still a pain to simplify though. i always have trouble remembering the addition formula for tangent, so i used . but i'm sure you'll get the answer doing it your way. your values for tanB and tanC are correct