不查表求值cos40チ0ニ2(1+√3tan10チ0ニ2)
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![不查表求值cos40チ0ニ2(1+√3tan10チ0ニ2)](/uploads/image/z/13947417-9-7.jpg?t=%E4%B8%8D%E6%9F%A5%E8%A1%A8%E6%B1%82%E5%80%BCcos40%26%2365409%3B0%26%2365414%3B2%281%2B%E2%88%9A3tan10%26%2365409%3B0%26%2365414%3B2%29)
不查表求值cos40チ0ニ2(1+√3tan10チ0ニ2)
不查表求值cos40チ0ニ2(1+√3tan10チ0ニ2)
不查表求值cos40チ0ニ2(1+√3tan10チ0ニ2)
cos40°(1+√3tan10°)
=cos40°·[(cos10°+√3sin10°)/cos10°]
=cos40°[2(sin30°cos10°+cos30°sin10°)/cos10°]
=(2cos40°sin40°)/cos10°
=sin80°/cos10°
=cos10°/cos10°
=1.