优优班--学霸训练营 > 知识点挑题
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            • 1.
              已知\(\tan ( \dfrac {π}{2}-θ)=4\cos (2π-θ)\),\(|θ| < \dfrac {π}{2}\),则\(\tan 2θ=(\)  \()\)
              A.\(- \dfrac { \sqrt {15}}{7}\)
              B.\( \dfrac { \sqrt {15}}{7}\)
              C.\(- \dfrac { \sqrt {15}}{8}\)
              D.\( \dfrac { \sqrt {15}}{8}\)
            • 2.
              如果\(α\)为锐角,\(\sin α= \dfrac {4}{5}\),那么\(\sin 2α\)的值等于\((\)  \()\)
              A.\( \dfrac {24}{25}\)
              B.\( \dfrac {12}{25}\)
              C.\(- \dfrac {12}{25}\)
              D.\(- \dfrac {24}{25}\)
            • 3.
              若\(\sin α= \dfrac {1}{3}\),则\(\cos 2α=(\)  \()\)
              A.\( \dfrac {8}{9}\)
              B.\( \dfrac {7}{9}\)
              C.\(- \dfrac {7}{9}\)
              D.\(- \dfrac {8}{9}\)
            • 4.
              已知\(\cos (α+ \dfrac {π}{2})= \dfrac {3}{5}\),则\(\cos 2α=(\)  \()\)
              A.\(- \dfrac {1}{5}\)
              B.\( \dfrac {1}{5}\)
              C.\(- \dfrac {7}{25}\)
              D.\( \dfrac {7}{25}\)
            • 5.
              若\(\sin α= \dfrac {1}{3}\),且\( \dfrac {π}{2} < α < π\),则\(\sin 2α=(\)  \()\)
              A.\(- \dfrac {2 \sqrt {2}}{9}\)
              B.\(- \dfrac {4 \sqrt {2}}{9}\)
              C.\( \dfrac {4 \sqrt {2}}{9}\)
              D.\( \dfrac {2 \sqrt {2}}{9}\)
            • 6.
              已知\(\cos α= \dfrac {2 \sqrt {5}}{5}\),则\(\cos 2α\)的值为\((\)  \()\)
              A.\(- \dfrac {4}{5}\)
              B.\( \dfrac {4}{5}\)
              C.\(- \dfrac {3}{5}\)
              D.\( \dfrac {3}{5}\)
            • 7.
              已知\(\tan α+ \dfrac {1}{\tan \alpha }= \dfrac {5}{2}\),\(α∈( \dfrac {π}{4}, \dfrac {π}{2})\),则\(\sin (2α- \dfrac {π}{4})\)的值为\((\)  \()\)
              A.\(- \dfrac {7 \sqrt {2}}{10}\)
              B.\( \dfrac { \sqrt {2}}{10}\)
              C.\(- \dfrac { \sqrt {2}}{10}\)
              D.\( \dfrac {7 \sqrt {2}}{10}\)
            • 8.
              已知\(\tan x=2\),求\(\cos 2x=\) ______ .
            • 9.
              已知函数\(f(x)=\sin x\cos x\),那么\(f(x)\)的最小正周期是 ______ .
            • 10.
              点\(A(\cos 2018^{\circ},\sin 2018^{\circ})\)在直角坐标平面上位于\((\)  \()\)
              A.第一象限
              B.第二象限
              C.第三象限
              D.第四象限
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