6.
已知角\(\alpha\)的终边经过点\(P(m{,}2\sqrt{2}){,}\sin\alpha{=}\dfrac{2\sqrt{2}}{3}\)且\(\alpha\)为第二象限.
\((1)\)求\(m\)的值;
\((2)\)若\(\tan\beta{=}\sqrt{2}\),求\(\dfrac{\sin\alpha\cos\beta{+}3\sin(\dfrac{\pi}{2}{+}\alpha)\sin\beta}{\cos(\pi{+}\alpha)\cos({-}\beta){-}3\sin\alpha\sin\beta}\)的值.