2)tg(7π/6)=tg(π+(π/6))=tg(π/6)=sqrt(3)/3
3) cos(5π/3)=cos(2π-(π/3)=cos(π/3)=1/2
4)ctg2,5π=ctg(2π+(π/2))=ctg(π/2)=0
5)cos(-47π/6)=cos((-48π+π)/6)=cos(-8π+(π/6))=cos(π/6)=sqrt(3)/2
6)sin(-8π/3)=sin((-9π+π)/3)=sin(-3π+(π/3))=sin(π/3)=sqrt(3)/2
7)tg(-2π/3)=tg((-3π+π)/3)=tg(-π+(π/3)=tg(π/3)=sqrt(3)
8) ctg(-7π/4)=ctg((-8π+π)/4)=ctg(-2π+(π/4)=ctg(π/4)=1