088du8
幼苗
共回答了15个问题采纳率:86.7% 举报
m dot n=(sin(x/4),cos(x/4)) dot (sqrt(3)cos(x/4),cos(x/4))
=(sqrt(3)/2)*sin(x/2)+(1+cos(x/2)/2=1
即:(sqrt(3)/2)*sin(x/2)+cos(x/2)/2=1/2
即:sin(x/2+π/6)=1/2
cos(x+π/3)=cos(2(x/2+π/6))=1-2sin(x/2+π/6)^2=1-2*(1/4)=1/2
1年前
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