7.
\((1)\)计算:\({{\log }_{3}}\sqrt{27}+\lg 4+\lg 25+{{\left( -\dfrac{1}{8} \right)}^{0}}=\)_____________
\((2)\)若\(a,b\)均为单位向量,且\(a\)与\(b\)的夹角为\({{120}^{\circ }}\),则\(a-b\)与\(b\)的夹角等于______.
\((3)\)若\(\alpha \in \left( 0,\pi \right)\),且\(\dfrac{1}{2}\cos 2\alpha =\sin \left( \dfrac{\pi }{4}+\alpha \right)\),则\(\sin 2\alpha \)的值为____________
\((4)\)锐角三角形\(\Delta ABC\)中,若\(A=2B\),\(a,b\)分别是角\(A,B\)所对边,
\(①\sin 3B=\sin C\) \(②\tan \dfrac{3B}{2}\tan \dfrac{C}{2}=1\) \(③\dfrac{\pi }{6} < B < \dfrac{\pi }{4}\) \(④\dfrac{a}{b}\in [\sqrt{2},\sqrt{3}]\)
则下列叙述正确的是_________