设\(x_{1}\),\(x_{2}∈(0,\dfrac{π}{2} )\),且\(x_{1}\neq x_{2}\),下列不等式中成立的是\((\) \()\)
\(①\dfrac{1}{2}\left(\sin {x}_{1}+\sin {x}_{2}\right) > \sin \dfrac{{x}_{1}+{x}_{2}}{2} \);
\(②\dfrac{1}{2} (\cos x_{1}+\cos x_{2}) > \cos \dfrac{{x}_{1}+{x}_{2}}{2} \);
\(③\dfrac{1}{2} (\tan x_{1}+\tan x_{2}) > \tan \dfrac{{x}_{1}+{x}_{2}}{2} \);
\(④\dfrac{1}{2} (\dfrac{1}{\tan {x}_{1}} +\dfrac{1}{\tan {x}_{2}} ) > \dfrac{1}{\tan \dfrac{{x}_{1}+{x}_{2}}{2}} \).