\((1)\)用数学归纳法证明：当\(n∈N^{*}\)时，\(\cos x+\cos 2x+\cos 3x+…+\cos nx= \dfrac {\sin (n+ \dfrac {1}{2})x}{2\sin \dfrac {1}{2}x}- \dfrac {1}{2}(x∈R\)，且\(x\neq 2kπ\)，\(k∈Z)\)；
\((2)\)求\(\sin \dfrac {π}{6}+2\sin \dfrac {2π}{6}+3\sin \dfrac {3π}{6}+4\sin \dfrac {4π}{6}+…+2018\sin \dfrac {2018π}{6}\)的值．