优优班--学霸训练营 > 知识点挑题
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            • 1.
              已知\(\sin 2α= \dfrac {2}{3}\),则\(\cos ^{2}(α+ \dfrac {π}{4})=(\)  \()\)
              A.\( \dfrac {1}{6}\)
              B.\( \dfrac {1}{3}\)
              C.\( \dfrac {1}{2}\)
              D.\( \dfrac {2}{3}\)
            • 2.
              下列各式中,值为\( \dfrac {1}{2}\)的是\((\)  \()\)
              A.\(\sin 15^{\circ}\cos 15^{\circ}\)
              B.\(\cos ^{2} \dfrac {π}{12}-\sin ^{2} \dfrac {π}{12}\)
              C.\( \sqrt { \dfrac {1+\cos \dfrac {π}{6}}{2}}\)
              D.\( \dfrac {\tan 22.5 ^{\circ} }{1-\tan ^{2}22.5 ^\circ }\)
            • 3.
              已知\(α∈R,\sin α+2\cos α= \dfrac { \sqrt {10}}{2}\),则\(\tan α=\) ______ .
            • 4.
              若\( \dfrac {1+\cos α}{\sin \alpha }=3\),则\(\cos α-2\sin α=(\)  \()\)
              A.\(-1\)
              B.\(1\)
              C.\(- \dfrac {2}{5}\)
              D.\(-1\)或\(- \dfrac {2}{5}\)
            • 5.
              已知\(\tan ( \dfrac {π}{4}+α)= \dfrac {1}{2}\),则\( \dfrac {\sin 2α-\cos ^{2}α}{1+\cos 2\alpha }=\) ______ .
            • 6.
              \(\triangle ABC\)内角\(A\),\(B\),\(C\)的对边分别为\(a\),\(b\),\(c\),若\(a=5,B= \dfrac {π}{3},\cos A= \dfrac {11}{14}\),则\(\triangle ABC\)的面积\(S=(\)  \()\)
              A.\( \dfrac {10 \sqrt {3}}{3}\)
              B.\(10\)
              C.\(10 \sqrt {3}\)
              D.\(20 \sqrt {3}\)
            • 7.
              已知\(\tan α=2\),则\( \dfrac {\sin α+\cos α}{\sin \alpha -3\cos \alpha }\)的值为\((\)  \()\)
              A.\(-3\)
              B.\(3\)
              C.\( \dfrac {1}{3}\)
              D.\(- \dfrac {1}{3}\)
            • 8.
              若\(\sin α= \dfrac {5}{13}\),且\(α\)为第二象限角,则\(\tan α\)的值等于\((\)  \()\)
              A.\( \dfrac {12}{5}\)
              B.\(- \dfrac {12}{5}\)
              C.\( \dfrac {5}{12}\)
              D.\(- \dfrac {5}{12}\)
            • 9.
              已知\(\tan θ=2\),则\( \dfrac {\sin θ+\cos θ}{\sin \theta }+\sin ^{2}θ\)的值为\((\)  \()\)
              A.\( \dfrac {19}{5}\)
              B.\( \dfrac {16}{5}\)
              C.\( \dfrac {23}{10}\)
              D.\( \dfrac {17}{10}\)
            • 10.
              已知\(x∈(0, \dfrac {π}{6})\),\(y∈(0, \dfrac {π}{6})\),且\(x\tan y=2(1-\cos x)\),则\((\)  \()\)
              A.\(y < \dfrac {x}{4}\)
              B.\( \dfrac {x}{4} < y < \dfrac {x}{2}\)
              C.\( \dfrac {x}{2} < y < x\)
              D.\(y > x\)
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