求值:cos(25π /4)

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求值:cos(25π/4)求值:cos(25π/4)求值:cos(25π/4)=cos(π/4)=根号2/2cos(25π/4)=cos(π/4)=二分之根号二cos((6+1/4)π)=cos(6π

求值:cos(25π /4)
求值:cos(25π /4)

求值:cos(25π /4)
=cos(π/4)=根号2/2

cos(25π/4)=cos(π/4)=二分之根号二

cos((6+1/4)π)
=cos(6π+π/4)
=cos(π/4)
=2分之根号2

√ 2比2

cos (25pi /4) = cos (pi / 4)=根号2除以2