y=sin(x/2)
周期为4π,交点个数为2个.额答案好像是一个交点不会，2个。
y=1/2，sin(x/2)=1/2
x=π/3或5π/3有过程吗写一下吧上面写了啊。
sin(x/2)=1/2
x/2=π/6或5π/6

x=π/3或5π/3上面写了啊。
sin(x/2)=1/2
x/2=π/6或5π/6

x=π/3或5π/3