T=2π/(1/2)=4π
对称轴
2x+π/2=kπ+π/2
x=kπ/2 k∈N题目是y=sin(2x+5π/2)为什么会变成2x+π/2=kπ+π/2因为y=sin(2x+5π/2)=sin(2x+2π+π/2)=sin(2x++π/2)