共50条信息
化简\(\dfrac{\sin(2\pi{-}\alpha)\cos(\pi{+}\alpha)\cos(\dfrac{\pi}{2}{+}\alpha)\cos(\dfrac{11\pi}{2}{-}\alpha)}{\cos(\pi{-}\alpha)\sin(3\pi{-}\alpha)\sin({-}\pi{-}\alpha)\sin(\dfrac{9\pi}{2}{+}\alpha)\tan(\pi{+}\alpha)}{=}\)______ .
若\(\cos \left( \dfrac{\pi }{8}-\alpha \right)=\dfrac{1}{6}\),则\(\cos \left( \dfrac{3\pi }{4}+2\alpha \right)=\)( )
若\({{S}_{n}}=\sin \dfrac{\pi }{5}+\sin \dfrac{2\pi }{5}+\cdots +\sin \dfrac{(n-1)\pi }{5}+\sin \dfrac{n\pi }{5}(n∈N^{*})\),则\(S_{1}\),\(S_{2}\),\(…S_{2018}\)中为\(0\)的有\((\) \()\)个
要得到函数\(f(x)=\sin 2x \)的图象,只需将函数\(g(x)=\cos 2x \)的图象( )
在\(\Delta ABC\)中,内角\(A,B,C\)所对的边分别是\(a,b,c\) .
\((\)Ⅰ\()\)若\(c=2,C=\dfrac{\pi }{3}\),且\(\Delta ABC\)的面积\(S=\sqrt{3}\),求\(a,b\)的值;
\((\)Ⅱ\()\)若\(\sin C+\sin (B-A)=\sin 2A\),试判断\(\Delta ABC\)的形状.
下列三角函数式:\(①\sin \left(\begin{matrix} \begin{matrix}2nπ+ \dfrac{3π}{4} \end{matrix}\end{matrix}\right)\);\(②\cos \left(\begin{matrix} \begin{matrix}2nπ- \dfrac{π}{6} \end{matrix}\end{matrix}\right)\);\(③\sin \left(\begin{matrix} \begin{matrix}2nπ+ \dfrac{π}{3} \end{matrix}\end{matrix}\right)\);\(④\cos \left[\begin{matrix} \begin{matrix}(2n+1)π- \dfrac{π}{6} \end{matrix}\end{matrix}\right]\);\(⑤\sin \left[\begin{matrix} \begin{matrix}(2n-1)π- \dfrac{π}{3} \end{matrix}\end{matrix}\right].\)其中\(n\)\(∈Z\),则函数值与\(\sin \dfrac{π}{3}\)的值相同的是( )
\(\tan 405^{\circ}-\sin 450^{\circ}+\cos 750^{\circ}=\)________.
已知\((4{{k}^{2}}+3){{x}^{2}}-8{{k}^{2}}x+4{{k}^{2}}-12=0\)
\((1)\)求函数\(f(x)\)的单调增区间;
\((2)\)已知锐角\(\Delta ABC\)的内角\(l\)的对边分别为\(a,b,c\),且\(f\left( A \right)=-\sqrt{3}\),\(a=3\),求\(s=\dfrac{1}{2}\sqrt{1+{{k}^{2}}}\dfrac{4}{\sqrt{1+4{{k}^{2}}}}\dfrac{\left| k-1 \right|}{\sqrt{{{k}^{2}}+1}}\)边上的高的最大值.
设\(\triangle \)\(ABC\)的三个内角为 \(A\), \(B\), \(C\),向量\(m\) \(=\)\(\left( \sqrt{3}\sin A,\sin B\right), n\) \(=\)\((\cos \)\(B\)\(, \sqrt{3}\cos A), \)若\(m·n\) \(=\)\(1\) \(+\)\(\cos ( \)\(A+B\)\()\),则 \(C=\) .
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