函数f(x)=(sinx)^4+(cosx)^2的最小正周期为?

2025-06-20 13:29:38
推荐回答(3个)
回答1:

y=(sinx)^4+(cosx)^4
=(sin²x+cos²x)²-2sin²xcos²x
=1-0.5[2sinxcosx]²
=1-0.5sin²2x
=1-0.25[1-cos4x]
=0.75+0.25cos4x
最小正周期是T=2π/4=π/2

回答2:

y=(sinx)^4+(cosx)^4
=(sin²x+cos²x)²-2sin²xcos²x
=1-(1/2)[2sinxcosx]²
=1-(1/2)sin²2x
=1-(1/4)[1-cos4x]
=(3/4)+(1/4)cos4x
最小正周期是2π/4=π/2

回答3:

f(x)=(sinx)^4+(cosx)^2
=(sinx)^4-(sinx)^2+1
=(sinx)^2[(sinx)^2-1]+1
=-(sinx)^2*(cosx)^2+1
=-(sin2x)^2/4+1
=(cos4x-1)/8+1
=====> T=2π/4=π/2