1
32sin20*cos20/cos20*cos(90-20)=32sin20/sin20=32
2
(-3cosa+cosa)/(-cosa)=-2cosa/(-cosa)=2
3
2cos2a=2*(1-2sin²a)=2*(1-2*0,49)=2*(1-0,98)=2*0,2=0,4
4
12/(sin²35+cos²(180+35))=12/(sin²35+cos²35)=12/1=12
5
-50tg9*tg(90-9)+31=-50*tg9*ctg9+31=-50*1+31=-50+31=-19