Question

tg9 градусов tg63градусов tg81 градусов tg27 градусов

Answer 1

$tg9\cdot tg63\cdot tg81\cdot tg27=(tg9\cdot tg81)\cdot (tg63\cdot tg27)=\\\\=(tg9\cdot tg(90-9))\cdot (tg63\cdot tg(90-63))=\\\\=(tg9\cdot ctg9)\cdot (tg63\cdot ctg63)=1\cdot 1=1\\\\\\\star \; \; \; tg \alpha \cdot ctg \alpha =1\; \; \star$