1.
如图,已知抛物线 \(C\):\({y}^{2}=2px \) 和\(⊙M \):\({\left(x-4\right)}^{2}+{y}^{2}=1 \),过抛物线\(C\)上一点\(H\left({x}_{0}\;,\;{y}_{0}\right)\left({y}_{0}\geqslant 1\right) \) 作两条直线与\(⊙M \)相切于\(A\),\(B\)两点,分别交抛物线为\(E\),\(F\)两点,圆心点\(M\)到抛物线准线的距离为\( \dfrac{17}{4} \).
\((1)\)求抛物线\(C\)的方程;
\((2)\)当\(∠AHB \)的角平分线垂直\(x\)轴时,求直线\(EF\)的斜率;
\((3)\)若直线\(AB\)在\(y\)轴上的截距为\(t\),求\(t\)的最小值.