Question

如图是函数y=sin(wx+φ) (|φ|＜π/2)的图象的一部分，那么

A. w=11/6, φ=π/6
B. w=11/6, φ=-π/6
C.w=2, φ=π/6
D.w=2, φ=-π/6

Answer 1

f(0)=1/2
f(π)=0
sinφ=1/2

φ=2kπ+(π/6)或φ=2kπ+(5π/6)

∵|φ|＜π/2
∴φ=π/6

sin(wπ+π/6)=0
wπ+π/6=2kπ或wπ+π/6=2kπ+π
w=2k-(1/6)或w=2k-(5/6)
根据题目选项
w=11π/6,φ=π/6

追问

谢谢，怎么由w=2k-(1/6)或w=2k-(5/6) 就知道w=11/6啊？

追答

选项里只有11π/6能满足w=2k-(1/6)或w=2k-(5/6)
若果有其他选项 另当别论