共50条信息
\((2)\)若\(f(x)=-1\),求\(\cos (\dfrac{2\pi }{3}-2x)\)的值.
已知\(\Delta ABC\)的内角\(A,B,C\)的对边分别为\(a,b,c\),且\(b\tan B=\sqrt{3}\left( a\cos C+c\cos A \right).\)
\((1)\)求角\(B\)的值;
\((2)\)若\(\Delta ABC\)的面积为\(\dfrac{7\sqrt{3}}{3},a+c=8\),求边\(b\).
在平面直角坐标系中,角\(α \)的终边经过点\(p\left(1,2\right) \)
\((1)\)求\(\tan α \)的值;
\((2)\)求\( \dfrac{\sin \left(π-α\right)+2\cos α}{2\cos \left( \dfrac{π}{2}-α\right)-\sin \left( \dfrac{π}{2}+α\right)} \)的值.
\((2)\)求\(\sin \left(α-5π\right)\sin \left( \dfrac{3π}{2}-α\right) \)的值
在平面直角坐标系中,锐角\(\alpha \)的终边与圆心在坐标原点的单位圆交于点\(A\),已知点\(A\)的纵坐标为\(\dfrac{4}{5}\).
\((\)Ⅰ\()\)求\(\sin \alpha \),\(\cos \alpha \);
\((\)Ⅱ\()\)求\(\dfrac{\sin (2\pi +\alpha )\cdot \cos (\pi +\alpha )\cdot \tan (3\pi -\alpha )}{\cos (\dfrac{\pi }{2}-\alpha )\cdot \tan (-\pi -\alpha )}\)的值.
(本小题满分10分)设圆满足:
(Ⅰ)截y轴所得弦长为2;
(Ⅱ)被x轴分成两段圆弧,其弧长的比为3∶1.
在满足条件(Ⅰ)、(Ⅱ)的所有圆中,求圆心到直线l:x-2y=0的距离最小的圆的方程.
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