根据下列条件求函数f(x)=sin(x+π/4)+2sin(x-π/4)-4cos 2x+3cos(x+3π/4)的值

根据下列条件求函数f(x)=sin(x+π/4)+2sin(x-π/4)-4cos 2x+3cos(x+3π/4)的值
(1)x=π/4
(2)x=3π/4
hou_MING_ZHOU 1年前 已收到1个回答 举报

小新猫猫8453 幼苗

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f(π/4)
=sin(π/4+π/4)+2sin(π/4-π/4)-4cosπ/2+3cos(π/4+3π/4)
=sinπ/2+2sin0-4cosπ/2+3cosπ
=1+0-0-3
=-2
f(3π/4)
=sin(3π/4+π/4)+2sin(3π/4-π/4)-4cos3π/2+3cos(3π/4+3π/4)
=sinπ+2sinπ/2-4cos3π/2+3cos3π/2
=0+2-0+0
=2

1年前

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