共50条信息
给出下列等式:\(①\arcsin \dfrac{\pi }{2}=1\);\(②\arcsin \left( -\dfrac{1}{2} \right)=-\dfrac{\pi }{6}\);\(③\arcsin \left( \sin \dfrac{\pi }{3} \right)=\dfrac{\pi }{3}\);\(④\sin \left( arc\sin \dfrac{1}{2} \right)=\dfrac{1}{2}\),其中正确等式的个数是\((\) \()\)
若角\(α\)是三角形的一个内角,且\(\sin α= \dfrac{1}{3}\),则\(α\)等于\((\) \()\)
已知\(0 < α < \)\(\dfrac{\pi }{{2}}\) \( < β < π\),\(\tan \dfrac{α}{2}= \dfrac{1}{2},\cos (β-α)= \dfrac{ \sqrt{2}}{10} \)
\((1)\)求\(\dfrac{\cos 2\alpha }{\sqrt{2}\cos (\dfrac{\pi }{4}+\alpha )\sin \alpha }\) 的值
\((2)\)求\(β\)的值
已知方程\(6{{x}^{2}}+5x+1=0\)的两实根为\(mn\),则\(\arctan m+\arctan n=\) ________.
进入组卷