共50条信息
若角\(\alpha{∈}({-}\pi{,}{-}\dfrac{\pi}{2})\),则\(\sqrt{\dfrac{1{+}\cos\alpha}{1{-}\cos\alpha}}{-}\sqrt{\dfrac{1{-}\cos\alpha}{1{+}\cos\alpha}}{=}({ })\)
函数\(f(x)=\sin ^{4}x+\cos ^{2}x\)的最小正周期是\((\) \()\)
若\(\cos a=- \dfrac{4}{5} \) ,\(a\)是第三象限的角,则\( \dfrac{1+\tan \dfrac{a}{2}}{1-\tan \dfrac{a}{2}}= (\) \()\)
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