/>分子化简:
2(cosx)^4 - 2(cosx)^2 + 1/2
=1/2*[4(cosx)^4 - 4(cosx)^2 + 1]
=1/2*[2(cosx)^2 - 1]^2
=1/2*(cos2x)^2
分母化简:
2tan(π/4 - x)[sin(x+π/4)]^2
=2tan(π/4-x)[cos(π/2-x-π/4)]^2
=2tan(π/4-x)[cos(π/4-x)]^2 ‘注:sinα=tanα*cosα
=2sin(π/4-x)cos(π/4-x)
=sin2(π/4-x)
=sin(π/2-2x)
=cos(2x)
所以,化简后,可以得到:
1/2*(cos2x)^2/cos(2x)
=1/2cos(2x)