函数模型. 1.三角函数的周期性 y=asin(ωx+φ) (ω≠0)的周期是t=________; y=acos(ωx+φ) (ω≠0)的周期是t=________; y=atan(ωx+φ) (ω≠0)的周期是t=________. 2.函数y=asin(ωx+φ)+k (a>0,ω>0)的性质 (1)ymax=________,ymin=________. (2)a=________________,k=________________. (3)ω可由________________确定,其中周期t可观察图象获得.