sin(x+270)= 求解析一下! sin(a-270°)怎么化简。三角函数的诱导公式。步骤简单...
sin\uff08x+y\uff09\u6c42\u5bfc\uff0c\u516c\u5f0f\u7b80\u5355\u8bf4\u4e00\u4e0b\u8c22\u8c22\u3002\u590d\u5408\u51fd\u6570\u6c42\u5bfc\u6cd5\u5219\uff0c
\u770b\u6210sinu\uff0cu=x+y\u6c42\u5bfc\uff0c
=cosu*u'
=cos(x+y)*(1+y')
\u89e3\u7531sin(a-270\u00b0)
=sin[-(270\u00b0-a)]\uff08\u7406\u8bbasin\uff08-x\uff09=-sinx\uff09
=-sin(270\u00b0-a)
=-[-cosa]........(\u7406\u8bbasin\uff083\u03c0/2-a\uff09=-cosa)
=cosa
sin(x+270°) = sin(x+270°-360°) = sin(x-90°) = -sin(90°-x) = -cos(x)
即:sin(x+270°) = - cos(x)
270度=360度-90度 所以括号里就是x+90
根据“奇变偶不变,符号看象限”得出-cosx
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