Вычислитьtg9°-tg63°+tg81°-tg27°

tg9-tg63+tg81-tg27=tg9+tg81- (tg27+tg63)=tg9+tg (90-9) — (tg27+tg (90-27)=tg9+Ctg9 — (tg27+Ctg)=1/ (cos9*sin9) -1/ (cos27*sin27)=2/sin18 — 2/sin54=2*(sin54-sin18) / (sin18*cos36)=2*2*sin18*cos36/ (sin18*cos36)=4