①-17π/3 =-18π/3+π/3=-6π+π/3所以sin(-17π/3)=sin(-6π+π/3)=sin(π/3)=√3/2cos(-17π/3)=cos(π/3)=1/2tan(-17π/3)=tan(π/3))=√3②21π/4 =16π/4+5π/4=4π+5π/4sin(21π/4)=sin(4π+5π/4)=sin(...