3sina=1+cosa
∴ 6*sin(a/2)*cos(a/2)=2cos²(a/2)
∴ 3sin(a/2)*cos(a/2)=cos²(a/2)
(1)cos(a/2)=0,则cot(a/2)=cos(a/2)/sin(a/2)=0
(2)cos(a/2)≠0,则3sin(a/2)=cos(a/2),∴ cot(a/2)=cos(a/2)/sin(a/2)=3
即cot(a/2)=0或cot(a/2)=3
3sina=1+cosa
∴ 6*sin(a/2)*cos(a/2)=2cos²(a/2)
∴ 3sin(a/2)*cos(a/2)=cos²(a/2)
(1)cos(a/2)=0,则cot(a/2)=cos(a/2)/sin(a/2)=0
(2)cos(a/2)≠0,则3sin(a/2)=cos(a/2),∴ cot(a/2)=cos(a/2)/sin(a/2)=3
即cot(a/2)=0或cot(a/2)=3