题目内容：

计算tan(－1560度)cos(17π/6)

优质解答

tan(-1560º)cos(17π/6)=tan(-1800º+240º)cos(17π/6-2π)=tan(240º)cos(5π/6)=tan(180º+60º)×cos(5π/6)=tan60ºcos(5π/6)=(√3)×(-√3/2)=-1.5