2cos75*sin75=6-sin^2α-cos^2α=(-1+sin^2α)*tg^2α1-tg67*tg7/tg67-tg7=

1)sin150=sin(180-30)=sin30=1/22)6-(sin²a+cos²a)=6-1=53)-cos²a*sin²a/cos²a=-sin²a4)cos74/cos67*cos7:sin60/cos67*cos7=cos74/cos67*cos7*cos67*cos7/sin60=cos74:√3/2=2cos74/√3=(2√3cos74)/3По формулам:1-tgatgb=cos(a+b)/cosacosbtga-tgb=sin(a-b)/cosacosb