高中数学 :以下三角函数详细转换过程
(1)1/2sinwx+1/2cos2wx+2=(根号2)/2(sin2w+π/4)1/2(2)-sin2x+cos2x=根号2cos(2x+4/π)...
(1)1/2sinwx+1/2cos2wx+2=(根号2)/2(sin2w+π/4)1/2
(2) -sin2x+cos2x=根号2cos(2x+4/π) 展开
(2) -sin2x+cos2x=根号2cos(2x+4/π) 展开
展开全部
都是要用辅助角公式:asinα+bcosα=√(a^2+b^2)sin(α+φ)
(1)1/2sinwx+1/2cos2wx+2
=√2/2(√2/2sinwx+√2/2cos2wx)+2
=√2/2(cosπ/4sinwx+sinπ/4cos2wx)+2
=√2/2sin(wx+π/4)+2
(2)-sin2x+cos2x
=cos2x-sin2x
=√2(√2/2cos2x-√2/2sin2x)
=√2(cosπ/4cos2x-sinπ/4sin2x)
=√2·cos(2x+4/π)
(1)1/2sinwx+1/2cos2wx+2
=√2/2(√2/2sinwx+√2/2cos2wx)+2
=√2/2(cosπ/4sinwx+sinπ/4cos2wx)+2
=√2/2sin(wx+π/4)+2
(2)-sin2x+cos2x
=cos2x-sin2x
=√2(√2/2cos2x-√2/2sin2x)
=√2(cosπ/4cos2x-sinπ/4sin2x)
=√2·cos(2x+4/π)
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