共50条信息
在\(\triangle ABC\)中,\(2a\cos A+b\cos C+c\cos B=0\),则角\(A\)的大小为( )
若\(\cos (\dfrac{\pi }{8}-\alpha )=\dfrac{1}{6}\),则\(\cos (\dfrac{3\pi }{4}+2\alpha )\)的值为 \((\) \()\)
在三角形\(ABC\)中,若\(A\)为钝角,则\(\tan B\tan C\)的值为( )
化简\(\dfrac{\sin(2\pi{-}\alpha)\cos(\pi{+}\alpha)\cos(\dfrac{\pi}{2}{+}\alpha)\cos(\dfrac{11\pi}{2}{-}\alpha)}{\cos(\pi{-}\alpha)\sin(3\pi{-}\alpha)\sin({-}\pi{-}\alpha)\sin(\dfrac{9\pi}{2}{+}\alpha)\tan(\pi{+}\alpha)}{=}\)______ .
代数式\(\sin 15{}^\circ \cos 75{}^\circ +\cos 15{}^\circ \sin 105{}^\circ =\)________.
进入组卷