Question

第一小题，求解，谢谢！

Answer 1

（1）原式=2sin50°(cos10°×1/2 + sin10°×根号3/2)/cos10°
=2sin50°(cos10°cos60°+sin10°sin60°)/cos10°
=2sin50°cos50°/cos10°
=sin100°/cos10°
=sin(90°+10°)/cos10°
=cos10°/cos10°
=1

Answer 2

能清楚点不？
那是sin60还是sin80
（1+√3tan10）还是（1+√3cos10）？？？

追问

sin50

追答

sin50（1+√3tan10）？是的话，继续
=sin50°（cos10°/cos10°+√3sin10°/cos10°）
=sin50°（cos10°+√3sin10°）/cos10°
=sin50°2（1/2cos10°+√3/2sin10°）/cos10°
=sin50°2（sin30°cos10°+cos30°sin10°）/cos10°
=sin50°2（sin（30°+10°））/cos10°
=sin50°2sin40°/cos10°
=2cos40°sin40°/cos10°
=sin80°/cos10°
=cos10°/cos10°
=1
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