\((1)\)已知\((x-y+3)^{2}+ \sqrt{2-y} =0\),则\(x+y=\)______.
\((2)\)已知\(\triangle ABC\)中,\(AB=5 cm\),\(BC=12 cm\),\(AC=13 cm\),那么\(AC\)边上的中线\(BD\)的长为______\(cm\).
\((3)\)函数的三种表示方法是_____、______、 .
\((4)\)如图所示,小红从家去书店,又去学校取封信后马上回家,其中\(x\)表示时间,\(y\)表示小红离她家的距离,则小红从学校回家的平均速度为 .
\((5)\)如图,在矩形\(ABCD\)中,\(AB=8\),\(BC=10\),\(E\)是\(AB\)上一点,将矩形\(ABCD\)沿\(CE\)折叠后,点\(B\)落在\(AD\)边的点\(F\)上,则\(DF\)的长为____________.
\((6)\)如图,已知在\(Rt\triangle ABC\)中,\(∠ACB=90^{\circ}\),\(AB=4\),分别以\(AC\),\(BC\)为直径作半圆,面积分别记为\(S_{1}\),\(S_{2}\),则\(S_{1}+S_{2}\)等于____________.
\((7)\)如图,直线\(a\)经过正方形\(ABCD\)的顶点\(A\),分别过顶点\(B\),\(D\)作\(DE⊥a\)于点\(E\),\(BF⊥a\)于点\(F\),若\(DE=4\),\(BF=3\),则\(EF\)的长为_______.
\((8)\)如图,在图\(1\)中,\(A_{1}\),\(B_{1}\),\(C_{1}\)分别是\(\triangle ABC\)的边\(BC\),\(CA\),\(AB\)的中点,在图\(2\)中,\(A_{2}\),\(B_{2}\),\(C_{2}\)分别是\(\triangle A_{1}B_{1}C_{1}\)的边\(B_{1}C_{1}\),\(C_{1}A_{1}\),\(A_{1}B_{1}\)的中点,\(…\),按此规律,则第\(n\)个图形中平行四边形的个数共有____________个.