7．
\((1)\) \(\sin \)\(11^{\circ}\)\(\cos \)\(19^{\circ}+\)\(\cos \)\(11^{\circ}\)\(\sin \)\(19^{\circ}\)的值是 ______．
\((2)\)函数\(f\)\((\)\(x\)\()=3\)\(\cos \)\(( \dfrac{π}{2} \)\(x\)\(- \dfrac{π}{8} )\)的最小正周期为 ______．
\((3)\)已知角\(α\)终边上一点\(P(-12,5)\)，则\(\cos \)\(α= \)______．
\((4)\)已知向量\( \overset{→}{a} \)与\( \overset{→}{b} \)的夹角为\( \dfrac{2π}{3} \)，\(| \overset{→}{a}|= \sqrt{2} \)，则\( \overset{→}{a} \)在\( \overset{→}{b} \)方向上的投影为 ______．
\((5)\)若\(\tan \)\(α\)，\(\tan \)\(β\)是方程\(x\)\({\,\!}^{2}-3 \sqrt{3} \)\(x\)\(+4=0\)的两个根，则\(\tan \)\((α+β)= \)______．