y=Asin(ax+b)(a>0,A>0)T=2π/a递增区间[(2kπ/a)-(π/2a)-(b/a),(2kπ/a)+(π/2a)-(b/a)](k∈Z)递减区间[(2kπ/a)+(π/2a)-(b/a),(2kπ/a)+(3π/2a)-(b/a)](k∈Z)第一个周期2π