（1+根号3倍tan10度）乘cos40度等于多少………要过程……
问题描述：
（1+根号3倍tan10度）乘cos40度等于多少………要过程……
答
=2(sin30°+cos30°tna10°)cos40°
=2(sin30°+cos30°sin10°/cos10°)cos40°
=2sin(30°+10°）cos40°/cos10°
=2sin40°cos40°/ cos10°
=sin80°/cos10°
=cos10°/cos10°
=1