4[cos(π/2)+cos(2a)]=1
cos2a=1/4
sin^4a=(1-cos2a)^2/4=9/64
cos^4a=(1+cos2a)^2/4=25/64
sin^4a+cos^4a=34/64=17/32
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若8cos（π/4+α）×cos（π/4-α）=1,则sin4α+cos4α=
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