优优班--学霸训练营 > 知识点挑题
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            • 1.
              \(\triangle ABC\)的内角\(A\),\(B\),\(C\)的对边分别为\(a\),\(b\),\(c.\)若\(\triangle ABC\)的面积为\( \dfrac {a^{2}+b^{2}-c^{2}}{4}\),则\(C=(\)  \()\)
              A.\( \dfrac {π}{2}\)
              B.\( \dfrac {π}{3}\)
              C.\( \dfrac {π}{4}\)
              D.\( \dfrac {π}{6}\)
            • 2.
              在\(\triangle ABC\)中,角\(A\),\(B\),\(C\)所对的边分别为\(a\),\(b\),\(c.\)若\(a= \sqrt {7}\),\(b=2\),\(A=60^{\circ}\),则\(\sin B=\) ______ ,\(c=\) ______ .
            • 3.
              在\(\triangle ABC\)中,\(\cos \dfrac {C}{2}= \dfrac { \sqrt {5}}{5}\),\(BC=1\),\(AC=5\),则\(AB=(\)  \()\)
              A.\(4 \sqrt {2}\)
              B.\( \sqrt {30}\)
              C.\( \sqrt {29}\)
              D.\(2 \sqrt {5}\)
            • 4.
              \(\triangle ABC\)的内角\(A\),\(B\),\(C\)的对边分别为\(a\),\(b\),\(c.\)已知\(b\sin C+c\sin B=4a\sin B\sin C\),\(b^{2}+c^{2}-a^{2}=8\),则\(\triangle ABC\)的面积为 ______ .
            • 5.
              若\(\triangle ABC\)的面积为\( \dfrac { \sqrt {3}}{4}(a^{2}+c^{2}-b^{2})\),且\(∠C\)为钝角,则\(∠B=\) ______ ;\( \dfrac {c}{a}\)的取值范围是 ______ .
            • 6. 在△ABC中,内角A,B,C的对边分别为a,b,c,已知
              (1)若,求A;
              (2)若sinB=2sinA,求△ABC的面积.
            • 7. [已知锐角三角形ABC中,角A,B,C所对边分别为a,b,c满足
              (Ⅰ)求;  
               (Ⅱ)若AB是最大边,求cosC的取值范围.
            • 8.
              \(\triangle ABC\)的内角\(A\),\(B\),\(C\)的对边分别为\(a\),\(b\),\(c\),已知\(C=60^{\circ}\),\(b= \sqrt {6}\),\(c=3\),则\(A=\) ______
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