sin(x+π/6)=1/2,则cos(π/3-x)求值
问题描述：
sin(x+π/6)=1/2,则cos(π/3-x)
求值
答
sin(x+π/6)=1/2, cos(x+π/6)=±√3//2
cos(π/3-x)=sin[π/2-(π/6+x)]=sinπ/2cos(x+π/6)-cosπ/2sin(x+π/6)=±√3//2
答
利用诱导公式
cos(π/3-x)
=cos[π/2-(π/6+x)]
=sin(π/6+x)
=1/2