若cos2x=√2/3,则cos^4x+sin^4x=多少?
来源：学生作业帮助网 编辑：六六作业网 时间：2025/01/23 23:26:42
若cos2x=√2/3,则cos^4x+sin^4x=多少?若cos2x=√2/3,则cos^4x+sin^4x=多少?若cos2x=√2/3,则cos^4x+sin^4x=多少?cos^4x+sin
若cos2x=√2/3,则cos^4x+sin^4x=多少?
若cos2x=√2/3,则cos^4x+sin^4x=多少?
若cos2x=√2/3,则cos^4x+sin^4x=多少?
cos^4x+sin^4x
=[(1+cos²2x)/2]^2+[(1-cos²2x）/2]^2
然后带入cos2x=√2/3,
得到11/18
我算错了= =.决赛时候...粗心了..搞错符号了..
cos^4x+sin^4x-2cos²xsin²x+2cos²xsin²x
=(cos²x-sin²x)²+1/2sin²2x
=cos²2x+1/2（1-cos²2x)
=1/2cos²2x+1/2
=1/2*2/9+1/2
=1/9+1/2
=11/18
cos^4x+sin^4x=(sin²x+cos²x)²-2sinx²cos²x=1-(2sinxcosx)²/2
=1-(sin2x)²/2
(sin2x)²=1-(cos2x)²=1-2/9=7/9
原式=1-(7/9)/2=11/18
若cos2x=√2/3,则cos^4x+sin^4x=多少?
cos(x-π/2)=3/5.则cos2x=
三角函数运算 为什么 cos2x+cos( 4π/3 -2x)=cos( π/3 +2x)
化简y=(2cos^4x-3cos^2x+1)/cos2x
若tanX=2,则【sin2X+2cos2X】/【2cos²X-3sin2X-1】=
若cos(π/2+x)=4/5,则cos2x=
化简f(x)=cos(2x-π/3)-cos2x
cos2x=3/5.sin^4+cos^4x=?
证明：cos4x+4cos2x+3=8cos^4x
cos^2 x=(cos2x-1)/2
化简：cos4x*cos2x-cos^2*3x
cos(2x+π)=-cos2x吗
f(x)=√3(sin2x-cos2x)^2-cos(4x+π/3）+4（cos^4x+sin^4x)求最小正周期
若sin(x+4/π）/cos2x=-根号2,则cos(x+4/π)的值为?
tanx=-1/2,sin2x+cos2x/4cos^2x-3sin^2x+1=
tan(x-π/4)=2,求sin2x+2cos2x/2cos^x-3sin2x-1
为什么cos2x-sin2x=√2cos(2x+π/4)
cos2x-sin2x =√2cos(2x+π/4) 是怎么来的?