已知函数 f(x)=sin 3x 2 cos x 2 +cos 3x 2 sin x 2 +2co s 2 x
f(x)=(\u221a3)cos(3x-a)-sin(3x-a)\u662f\u5947\u51fd\u6570\uff0c\u5219a\uff1d\uff1f
\u8fd9\u4e2a\u7b80\u5355\u3002
\u9996\u5148\uff0c\u56e0\u4e3a\u662f\u5947\u51fd\u6570\uff0c\u6240\u4ee5f(0)=0
\u5f97\u5230\uff1a(\u221a3)cos(-a)-sin(-a)=0\uff0c\u4e5f\u5c31\u662f
(\u221a3)cos(a)+sin(a)=0\uff0c\u6240\u4ee5tan(a)=-\u221a3,
\u6240\u4ee5\uff0ca=-\u03c0/3+k\u03c0.(\u56e0\u4e3a\u6b63\u5207\u51fd\u6570\u662f\u4e00\u4e2a\u5468\u671f\u51fd\u6570\uff0c\u6240\u4ee5\u8981\u52a0\u4e0a\u5468\u671f)
