3.
下列命题中真命题的个数是\((\) \()\)
\(①\)函数\(y=\sin x\),其导函数是偶函数;
\(②\)“若\(x=y\),则\(x^{2}=y^{2}\)”的逆否命题为真命题;
\(③\)“\(x\geqslant 2\)”是“\(x^{2}-x-2\geqslant 0\)”成立的充要条件;
\(④\)命题\(p\):“\(∃x_{0}∈R\),\(x_{0}^{2}-x_{0}+1 < 0\)”,则命题\(p\)的否定为:“\(∀x∈R\),\(x^{2}-x+1\geqslant 0\)”.