sin2x等于什么
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sin2x+1=2tanx/(1+tan^2x)+1=4/5+1=9/5
tanx/tan2x=tanx/[2tanx/1-(tanx)^2]=[1-(tanx)^2]/2X趋近于π=[1-(tanπ)^2]/2=1/2sinx/sin2x=sinx/2sinxcosx=1
假设sin2x*[(根号1-tanx)+(根号1+tanx)]=2sin2x则(根号1-tanx)+(根号1+tanx)=2两边平方得1-tanx+1+tanx+2根号(1-tan^2x)=42根号(
(1)根据图信息可知sina=4/5cosa=3/5∴(sina^2+sin2a)/(cosa^2+cos2a)=(sina^2+2sinacosa)/(cosa^2+cosa^2-sina^2)=(
lim(x趋近0)(sin2x)/x=lim(x趋近0)(2sinxcosx)/x=lim(x趋近0)sinx/x*2cosx=1*2=2
f(sinx)=cos2x=1-2sin^2xf(x)=1-2x^2f(cosx)=1-2cos^2x=-cos2x选C
sinx=2cosx,sinx^2+(1/2sinx)^2=1,得sinx^2=4/5,sin2x=2sinxcosx=sinx^2=4/5希望采纳
cos^2x+2SINXCOSX+SIN^2X=1(SINX+COSX)^2=1SINX+COSX=1或-1希望对你帮助
sin^2x+cos^2x=1sin^2x+9sin^2x=1sin^2x=1/10Cos2X+Sin2X=cos^2x-sin^2x+2sinxcosx=9sin^2x-sin^2x+6sin^2x
cos(π/4-x)=3/5;cosxcosπ/4+sinxsinπ/4=3/5;(√2/2)cosx+(√2/2)sinx=3/5;两边平方得:1/2cos²x+1/2sin²x
因为tanx=sinx/cosx.所以tanx+1/tanx=4变形为sinx/cosx+cosx/sinx=4.通分得(sinx^2+cosx^2)/sinxcosx=4.又因为2sinxcosx=
3x在x趋于无穷时是无穷大量,sin2x是有界量,有界量除以无穷大量结果是无穷小量.极限是0.
tanx=3则:sinx/cosx=3sinx=3cosxsin2x/cos²x=2sinxcosx/cos²x=6cos²x/cos²x=6
题目条件不充分啊cos2x+sin2x=1cos2x=cos^2x-sin^2xsin2x=2sinxcosxcos2x+sin2x=cos^2x-sin^2x+2sinxcosx
x→0,2x→0,sin2x~2x∴lim(x→0)sin2x/3x=lim(x→0)2x/3x=2/3
sinx/cosx=tanx所以sin2x/cos2x=tan2x
sin2x+cos2x=√2(√2/2sin2x+√2/2*cos2x)=√2(cospai/4sin2x+sinpai/4cos2x)=√2sin(2x+pai&#4
设f(x)=sinx^2+sin2x-2cosx^2,此题实际上就是求f(x)的值域,具体解答如下:\x0df(x)=sinx^2+sin2x-2cosx^2\x0d=(sinx^2+cosx^2)+
1/2sin4x
sinx^2+cosx^2=1,这就相当于一个公式,中间的变数x当然可以换成任何值了!