sin70[1-根号3(tan50)]等于-1,
问题描述：
sin70[1-根号3(tan50)]等于-1,
答
sin70[1-根号3(tan50)]=sin70°（cos50°-根号3sin50°)/cos50°
=2sin70°sin(30°-50°）/cos50°=-2sin20°cos20°/sin40°
=-sin40°/sin40°=-1