sin750°=sin(720°+30°)=sin30°=1/2cos750°=cos(720°+30°)=cos30°=根号3/2tan750°=tan(720°+30°)=tan30°=根号3/3sin17π/4=sin(16π/4+π/4)=sin(π/4)=根号2/2cos17π/4=cos(16π/4+π/4)=cos(π/4)=根...