Question

已知函数f（x）=sin（ωx+φ）其中ω>0,|φ|＜π／2

若cosπ／4φ－sin3π／4sinφ＝0，求φ的值

Answer 1

cosπ／4cosφ－sin3π／4sinφ=cosπ／4cosφ－sinπ／4sinφ＝cos(φ+π/4)=0
φ+π/4=π/2 φ=π/4

Answer 2

cosπ/4cosφ-sin（3π/4)sinφ=0
cosπ/4cosφ-sinπ/4sinφ=0
cos(π/4 φ)=0
|φ|<π/2
所以π/4 φ=π/2
所以φ=π/4　　　望采纳~