9.
\((1)\)设点\(A(-2,0)\)和\(B(0,3)\),在直线\(l\):\(x\)\(-\)\(y\)\(+1=0\)上找一点\(P\),使\(|PA|+|PB|\)的取值最小,则这个最小值为 ______.
\((2)\)已知一圆的圆心坐标为\(C(2,-1)\),且被直线\(l\):\(x\)\(-\)\(y\)\(-1=0\)截得的弦长为\(2 \sqrt{2} \),则此圆的方程 ______.
\((5)\)已知\(A\),\(B\)均为钝角,且\(\sin A= \dfrac{ \sqrt{5}}{5},\sin B= \dfrac{ \sqrt{10}}{10} \),求\(A+B\)的值为 ______.
\((6)\)已知\(| \overset{→}{a} |=| \overset{→}{b} |=2\),\( \overset{→}{a} \)与\( \overset{→}{b} \)的夹角为\(60^{\circ}\),则\( \overset{→}{a} + \overset{→}{b} \)在\( \overset{→}{a} \)方向上的投影为 ______.