sin方2a+sin2acosa-cos2a=1sin方2a+sin2acosa-2(cosa)^2+1=14(sina)^2(cosa)^2+2sina(cosa)^2-2(cosa)^2=02(sina)^2+sina-1=0(2sina-1)(sina+1)=0sina=1/2cosa=√3/2tana=√3/3所以sinatana=√3/6