tan35度=m,则cos20度/(1-sin20度)=?麻烦写下过程
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tan35度=m,则cos20度/(1-sin20度)=?麻烦写下过程
tan35度=m,则cos20度/(1-sin20度)=?麻烦写下过程
tan35度=m,则cos20度/(1-sin20度)=?麻烦写下过程
cos20°/(1-sin20°)=sin70°/(1-cos70°)=1/tan35°=1/m
cos20°/(1-sin20°)=sin70°/(1-cos70°)
=2sin35°cos35°/(1-(1-2sin35°^2))=1/tan35°=1/m
cos20°/(1-sin20°)
=sin(90°-20°)/[1-cos(90°-20°)]
=sin70°/(1-cos70°)
=2sin35°cos35°/[1-(1-2sin35°)]
=2sin35°cos35°/2sin35°
=cos35°/sin35°
=1/tan35°
=1/m
你要用到的,就是倍角公式,如果你对这个公式不了解,建议你先看一下教材
cos20°/(1-sin20°)
=sin(90°-20°)/[1-cos(90°-20°)]
=sin70°/(1-cos70°)
=2sin35°cos35°/[1-(1-2sin35°)]
=2sin35°cos35°/2sin35°
=cos35°/sin35°
=1/tan35°
=1/m