sin4(π/8)+cos4(π/8)的值,

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sin4(π/8)+cos4(π/8)的值,
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sin4(π/8)+cos4(π/8)的值,
sin4(π/8)+cos4(π/8)的值,

sin4(π/8)+cos4(π/8)的值,
sin4(π/8)+cos4(π/8)
=[1-cos(π/4)]²/4+[1+cos(π/4)]²/4
=[2+2cos²(π/4)]/4
=[2+1+cos(π/2)]/4
=3/4

sin4(π/8)+cos4(π/8)
=[sin2(π/8)+cos2(π/8)]^2-2[sin(π/8)cos(π/8)]^2
=1-(1/2)[sin(π/4)]^2
=1-1/4
=3/4

=(sin^2(π/8)+cos^2(π/8))^2-2sin^2(π/8)cos^2(π/8)
=1-sin^2(π/4)/2
=1-1/4
=3/4