(1) cos(-1109°=cos1109 °.=cos(3*360 °+29°).=cos29°.( =0.8746).(2)sin(-1050)=-sin1050.=-sin(1080°-30°).=-sin(3*360°-30).=-(-sin30°.=sin30.=1/2.（ =0.50°）.(3) tan(19π/3)=tan(6π+π/3).=tan(3...