*香奈儿*
幼苗
共回答了19个问题采纳率:94.7% 举报
m//n,则:[sin(x-π/4)]/cos(x-π/4)=1/3,即:tan(x-π/4)=1/3
又:tan(x-π/4)=[tanx-1]/[tanx+1]=1/3,则:tanx=2
f(x)=sin(x-π/4)cos(x-π/4)+3=(1/2)sin(2x-π/2)+3=-(1/2)cos2x+3
tanx=2
f(x)=-(1/2)cos2x+3
计算下cos2x的值.
cos2x=cos²x-sin²x=(cos²x-sin²x)/(cos²x+sin²x)=[1-tan²x]/[1+tan²x]=-3/5
则:f(x)=33/10
g(x)=-(1/2)cos[2(x-m)]是奇函数,因奇函数有f(0)=0,则:
cos[-2m]=0
得:m的最小值是π/4
1年前
6