cos(x+π/6)=1/3,(0
问题描述：
cos(x+π/6)=1/3,(0
答
0
故cosx=cos[(x+π/6)-π/6]
=cos(x+π/6)cos(π/6)+sin(x+π/6)sin(π/6)
=(1/3)*(√3/2)+(2√2/3)*(1/2)
=(√3+2√2)/6