6.
\((1)\)若等比数列\(\{a_{n}\}\)满足\(a_{1}+a_{3}=20\),\(a_{2}+a_{4}=40\),则公比\(q= \)______.
\((2)\)函数\(y=\dfrac{{x}^{2}+3}{ \sqrt{{x}^{2}+2}} \)的最小值是______.
\((3)\)已知水平放置的\(\triangle ABC\)按“斜二测画法”得到如图所示的直观图,其中\(B′O′=C′O′=1\),\(∠BˈAˈCˈ=90^{\circ}\),则原\(\triangle ABC\)的面积为______.
\((4)\)如图,为测量山高\(MN\),选择\(A\)和另一座的山顶\(C\)为测量观测点,从\(A\)点测得\(M\)点的仰角\(∠AMN=60^{\circ}\),\(C\)点的仰角\(∠CAB=45^{\circ}\)以及\(∠MAC=75^{\circ}\);从\(C\)点测得\(∠MCA=60^{\circ}\),已知山高\(BC=1000m\),则山高\(MN= \)______ \(m\).