优优班--学霸训练营 > 知识点挑题
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            • 1.
              已知\(\cos ( \dfrac {π}{2}+α)= \dfrac {3}{5}\),且\(α∈( \dfrac {π}{2}, \dfrac {3π}{2})\),则\(\tan α=(\)  \()\)
              A.\( \dfrac {4}{3}\)
              B.\( \dfrac {3}{4}\)
              C.\(- \dfrac {3}{4}\)
              D.\(± \dfrac {3}{4}\)
            • 2.
              已知\(\sin x=3\cos x\),则\(\sin x\cos x\)的值是\((\)  \()\)
              A.\( \dfrac {1}{6}\)
              B.\( \dfrac {1}{5}\)
              C.\( \dfrac {3}{10}\)
              D.\( \dfrac {2}{9}\)
            • 3.
              已知\(\tan α=3\),则\( \dfrac {\sin α+\cos α}{\sin \alpha -\cos \alpha }=(\)  \()\)
              A.\(1\)
              B.\(2\)
              C.\(-1\)
              D.\(-2\)
            • 4.
              已知向量\( \overrightarrow{a}=(\sin x, \dfrac {3}{2})\),\( \overrightarrow{b}=(\cos x,-1)\)当\( \overrightarrow{a}/\!/ \overrightarrow{b}\)时,求\( \dfrac {2\sin x-\cos x}{4\sin x+3\cos x}\)的值.
            • 5.
              已知\(\cos (α-β)= \dfrac {3}{5}\),\(\sin β=- \dfrac {5}{13}\),且\(α(0, \dfrac {π}{2})\),\(β∈(- \dfrac {π}{2},0)\),则\(\sin α=\) ______ .
            • 6.
              \(y=(\sin x-\cos x)^{2}-1\)是\((\)  \()\)
              A.最小正周期为\(2π\)的偶函数
              B.最小正周期为\(2π\)的奇函数
              C.最小正周期为\(π\)的偶函数
              D.最小正周期为\(π\)的奇函数
            • 7.
              已知角\(α\)为第三象限角,且\(\tan α= \dfrac {3}{4}\),则\(\sin α+\cos α=(\)  \()\)
              A.\(- \dfrac {7}{5}\)
              B.\(- \dfrac {1}{5}\)
              C.\( \dfrac {1}{5}\)
              D.\( \dfrac {7}{5}\)
            • 8.
              记\(\cos (-80^{\circ})=k\),那么\(\tan 80^{\circ}=(\)  \()\)
              A.\( \dfrac { \sqrt {1-k^{2}}}{k}\)
              B.\(- \dfrac { \sqrt {1-k^{2}}}{k}\)
              C.\( \dfrac {k}{ \sqrt {1-k^{2}}}\)
              D.\(- \dfrac {k}{ \sqrt {1-k^{2}}}\)
            • 9.
              在\(\triangle ABC\)中,\(\sin A= \dfrac {5}{13}\),\(\cos B= \dfrac {3}{5}\),则\(\cos C=(\)  \()\)
              A.\(- \dfrac {16}{65}\)
              B.\(- \dfrac {56}{65}\)
              C.\(± \dfrac {16}{65}\)
              D.\(± \dfrac {56}{65}\)
            • 10.
              若\(\sin ^{2}α+\sin α=1\),则\(\cos ^{4}α+\cos ^{2}α=\) ______ .
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