tg(a+в)

If you mean tan(a + v) (tg(a+в)):

• Using tangent addition formula: tg(a+v) = (tg a + tg v) / (1 − tg a · tg v), valid when tan a and tan v are defined (cos a ≠ 0, cos v ≠ 0) and cos(a+v) ≠ 0.

• In sine/cosine form (always safe when defined): tg(a+v) = (sin a cos v + cos a sin v) / (cos a cos v − sin a sin v), valid when cos(a+v) ≠ 0.

If you provide values for a and v, I can compute a numeric result.