-cos(7/4) =cos(π-(7/4))
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-cos(7/4) =cos(π-(7/4))
![-cos(7/4) =cos(π-(7/4))](/uploads/image/z/19760528-56-8.jpg?t=-cos%287%2F4%29+%3Dcos%28%CF%80-%287%2F4%29%29)
cos(π-a)=-cos a
熟记诱导公式!
奇变偶不变,符号看象限!
熟记诱导公式!
奇变偶不变,符号看象限!
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cos(- 19/4 π)=?
已知cos(π4
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求函数y=7-4sinxcosx+4cos^2x-4cos^4x的最大值与最小值
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