9.
点\(P({{x}_{0}},{{y}_{0}})({{y}_{0}} > 4)\)是抛物线\({{x}^{2}}=4y\)上第一象限内的一点,过点\(P\)作圆\(E:{{x}^{2}}+{{(y-2)}^{2}}=4\)的两条切线,切点为\(M,N,\)分别交\(x\)轴于\(B,C\)两点,给出下列结论:\(①\left| PM \right|=\left| PN \right|={{y}_{0}};②\)若\({{y}_{0}}=9,\)则直线\(MN\)的方程是\(7x-6y-7=0\);\(③\)若\({{y}_{0}}=9,\)则\(\vartriangle PBC\)的面积是\(\dfrac{162}{5}\);\(④\vartriangle PBC\)的面积的最小值是\(30\),其中正确的是___________\(.(\)填写所有正确结论的编号\()\)