\((1)\)若单位向量\( \overrightarrow{{e}_{1},} \overrightarrow{{e}_{2}} \)的夹角为\( \dfrac{π}{3} \),则向量\( \overrightarrow{{e}_{1}}-2 \overrightarrow{{e}_{2}} \)与向量\( \overrightarrow{{e}_{1}} \)的夹角为 ______.
\((2)\)已知\(\theta \)是第四象限角,且\(\sin (θ+ \dfrac{π}{4})= \dfrac{3}{5},则\tan (θ- \dfrac{π}{4})= \)_____.
\((3)\)设\(\triangle ABC\)的内角\(A\),\(B\),\(C\)所对的边分别为\(a\),\(b\),\(c\),若三边的长为连续的三个正整数,且\(A > B > C\),\(3\)\(b\)\(=20\)\(a\cos \)\(A\),则\(\sin \)\(A\):\(\sin \)\(B\):\(\sin \)\(C\)为______.
\((4)\)已知函数\(f(x)={x}^{2}+ \dfrac{2}{x},g(x)=( \dfrac{1}{2}{)}^{x}+m \),若\(∀\)\(x\)\({\,\!}_{1}∈[1,2]\),\(∃\)\(x\)\({\,\!}_{2}∈[-1,1]\),使得\(f\)\((\)\(x\)\({\,\!}_{1})\geqslant \)\(g\)\((\)\(x\)\({\,\!}_{2})\),则实数\(m\)的取值范围是______.