7.
判断正误\((\)正确的打“\(√\)”,错误的打“\(×\)”\()\)
\((1)y=\cos x\)在第一、二象限内是减函数\(.(\) \()\)
\((2)\)若\(y=k\sin x+1\),\(x∈R\),则\(y\)的最大值是\(k+1.(\) \()\)
\((3)\)若非零实数\(T\)是函数\(f(x)\)的周期,则\(kT(k\)是非零整数\()\)也是函数\(f(x)\)的周期\(.(\) \()\)
\((4)\)函数\(y=\sin x\)图象的对称轴方程为\(x=2kπ+ \dfrac{π}{2}(k∈Z).(\) \()\)
\((5)\)函数\(y=\tan x\)在整个定义域上是增函数\(.(\) \()\)