= tg(n/2 +a) + tg(2n+a)
= (tg(n/2) tg(a) + 1) + (tg(2n) tg(a) + 1)
= (sin(n/2) / cos(n/2) sin(a) / cos(a) + 1) + (sin(2n) / cos(2n) sin(a) / cos(a) + 1)
= (sin(n) / (2 cos(n/2) cos(a)) + 1) + (2 sin(n) cos(n) / (2 cos(2n) cos(a)) + 1)
= (sin(n) / (2 sqrt((1 + cos(n)) (1 + cos(a)))) + 1) + (sqrt(2) sin(n) sqrt(1 - cos(n)^2) / (2 sqrt(2 cos(n)^2 - 1) * sqrt(1 - cos(a)^2)) + 1)

This is the final answer in terms of trigonometric functions.