共50条信息
\((1)\)已知\(\cos \beta =-\dfrac{3}{5}\),且\(\beta \)为第二象限角,求\(\sin \beta \)的值;
\((2)\)已知\(\dfrac{\tan \alpha }{\tan \alpha -6}=-1,\)求值:\(\dfrac{2\cos \alpha -3\sin \alpha }{3\cos \alpha +4\sin \alpha }.\)
已知\(\theta \)是锐角,那么\(2\theta \)是\((\) \()\)
进入组卷