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cosxcos2x等于多少
cos2x
=
cosx
答:
请采纳
∫
cosxcos2x
cos3xdx
答:
= (1/2)cos2xcos4x + (1/2)cos²2x = (1/2)(1/2)[cos(2x + 4x) + cos(2x - 4x)] + (1/2)(1/2)(1 + cos4x)= (1/4)cos6x + (1/4)cos2x + 1/4 + (1/4)cos4x ∫
cosxcos2x
cos3x dx = (1/4)∫ dx + (1/4)∫ cos2x dx + (1/4)∫ cos4x ...
cosxcos2x
cos4x化简过程
答:
原式乘以sinx,把原式化为sin8x/8 再除以sinx,即为cotπ/9/8
cosx
和
cos2x
的等价无穷小是什么?
答:
答:用二倍角公式:cos2a=1-2sin²a 1-cos2a=2sin²a 所以:1-
cosx
=2sin²(x/2)~2×(x/2)²~x²/2 所以:1-cosx的等价无穷小为x²/2
cosxcos2x
从负二分之拍到二分之拍的定积分
答:
你好!计算过程如图,先改写一下,再凑微分,答案是2/3。经济数学团队帮你解答,请及时采纳。谢谢!
cosx
和
cos2x
的关系?急
答:
cos2x
cos3x =(1/2)(2cos2xcos3x)=(1/2)(2cos2xcos3x+sin2xsin3x-sin2xsin3x)=(1/2)[(cos2xcos3x+sin2xsin3x)+(cos2xcos3x-sin2xsin3x)]=(1/2)[cos(3x+2x)+cos(3x-2x)]=1/2(cos5x+
cosx
)看在手打了这些的份上,请采纳~
2sinx
cosxcos2x
怎么化简?
答:
sin2x=2sinxcosx 2sinx
cosxcos2x
=sin2xcos2x =1/2sin4x
cosxcos2x
cos3x的不定积分
答:
解:∫
cosxcos2x
cos3xdx =1/2∫cosx*(cos(3x+2x)+cos(3x-2x))dx =1/2∫cosx*(cos5x+cosx)dx =1/2∫cosxcos5xdx+1/2∫(cosx)^2dx =1/4∫(cos(5x+x)+cos(5x-x))dx+1/4∫(1+cos2x)dx =1/4∫1dx+1/4∫cos2xdx+1/4∫cos6xdx+1/4∫cos4xdx =x/4+1/8sin2x+1/...
证明
cos 2x
cos x
=1/2(cos x+cos 3x)
答:
证明:等式右边=1/2(
cosx
+
cos2x
*cosx-sin2x*sinx)=1/2[cosx*(1+cos2x)-2(sinx)^2*cosx]=1/2[2*(cosx)^3-2(sinx)^2*cosx]=cosx*[(cosx)^2-(sinx)^2]=cosx*[2(cosx)^2-1]=cosx*cos2x=左边证明完毕
若
cos2x
+
cosx
=0,则sin2x的值
等于多少
?
答:
cos2x
+
cosx
=2cos�0�5x-1+cosx=0 (cosx+1)(2cosx-1)=0 cosx=-1,cosx=1/2 cosx=-1 则x=2kπ+π 2x=4kπ+2π 所以sin2x=0 cosx=1/2 x=2kπ+π/3,x=2kπ-π/3 2x=4kπ+2π/3,或2x=4kπ-2π/3 所以sin2x=sin2π/3=√3/2 或sin2x=sin-π/3=...
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