已知tan(3π/2 + α)=根号下3,那么cos（α+7/2π）=
问题描述：
已知tan(3π/2 + α)=根号下3,那么cos（α+7/2π）=
答
tan(3/2π+α) =√3;
tan(π+π/2+a)=tan(π/2+a)=-cota=√3;
cos(α+7/2π)=cos(a+3π/2+2π)=cos(a+3π/2)
=cos(a+π/2+π)=-cos(a+π/2)=sina=1/2