6.
\((1)\)不等式\({|}2{-}3x{|} \geqslant 4\)的解集为______ .
\((2)\)双曲线\(\dfrac{x^{2}}{a^{2}}{-}\dfrac{y^{2}}{9}{=}1(a{ > }0)\)的一条渐近线方程为\(y{=}\dfrac{3}{5}x\),则\(a{=}\) ______ .
\((3)\)点\(P\)是椭圆\(\dfrac{x^{2}}{16}{+}\dfrac{y^{2}}{9}{=}1\)上一点,\(F_{1}\),\(F_{2}\)分别是椭圆的左、右焦点,若\({|}PF_{1}{||}PF_{2}{|=}12\),则\({∠}F_{1}PF_{2}\)的大小______ .
\((4)\)已知椭圆\(\dfrac{x^{2}}{a^{2}}{+}\dfrac{y^{2}}{b^{2}}{=}1(a{ > }b{ > }0)\)的左、右焦点分别为\(F_{1}\),\(F_{2}\),过\(F_{1}\)且与\(x\)轴垂直的直线交椭圆于\(A\)、\(B\)两点,直线\(AF_{2}\)与椭圆的另一个交点为\(C\),若\(\overrightarrow{AF_{2}}{+}2\overrightarrow{CF_{2}}{=}\overset{{→}}{0}\),则椭圆的离心率为______ .