计算cos40°/(cos25°√1-sin40°)等于

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计算cos40°/(cos25°√1-sin40°)等于

计算cos40°/(cos25°√1-sin40°)等于
计算cos40°/(cos25°√1-sin40°)等于

计算cos40°/(cos25°√1-sin40°)等于
cos40°/(cos25°√1-sin40°)
=cos40°/[cos25°√(cos20°-sin20°)^2]
=cos40°/[cos25°(cos20°-sin20°)]
=(cos20°-sin20°)(cos20°+sin20°)/[cos25°(cos20°-sin20°)]
=(cos20°+sin20°)/cos25°
=√2 (cos20°sin45+sin20°cos45)/cos25°
=√2sin65°/cos25°
=√2