1. = sin(a)cos(a)-sin(a)sin(a)=sin(a)cos(a)-sin(a²)
2. a) sin10°+cos40°=sin10°+cos(90°-50°)=sin10°+sin50°=2sin30°cos(-20°)=2**cos20°=cos20°
б) tg40°+ctg20°=tg40°+tg70°=
3. =
cos48/4п=cosп/2=0
48/4=19/2=8,5