x2 3x-4 sin(x-1)

(1+cotx)sin^2x=sin^2x+sinxcosx2sin(x+π/4)sin(x-π/4)=根号2(sinx+cosx)*根号2/2(sinx-cosx)=sin^2x-cos^2xf(x

原式=sin[π-(5π/6-4x)]=sin(4x+π/6)=-sin(-4x-π/6)=-cos[π/2-(-4x-π/6)]=-cos(4x+2π/3)=-cos[2(2x+π/3)]=-[1-

sin(PI/6+2x)=cos(PI/2-PI/6-2x)=cos(PI/3-2x)=cos(2*(PI/6-x))=1-2*sin(PI/6-x)^2=1-2*(1/4)^2=7/8tan70*c

楼上都错了,图像没问题这个表达式实际是个常数,你可以运行TrigReduce[Sin[x]Sin[x+2]-Sin[x+1]^2]看看,结果为1/2(-1+Cos[2])只不过Plot的自动选择坐标系

2sin^2[(π/4)+x]+根号3（sin^x-cos^x）-1=-(1-2sin^2[(π/4)+x)-√3cos2x=-cos(π/2+2x)-√3cos2x=sin2x-√3cos2x=2[

原式=∫x*(csc^2x+1)=∫x*csc^2x+x（分开积分）前面=-x*cotx+∫cotx=-x*cotx+ln|sinx|后面=1/2x^2记得加C

用公式a³+b³=(a+b)(a²-ab+b²)cos^6x+sin^6x=(cos²x)³+(sin²x)³=(cos

∫sinx/(1+sin^4x)dx=∫dcosx/(1+(1-cos^2x)^2)=∫dcosx/(2-2cos^2x+cos^4x)=∫du/(2-2u^2+u^4)=.查不定积分表吧再问：积分表

答案：cosx=-1或cosx=1/4根据和差化积公式,[sin(x+120°)-sin(x-120°)]/sin(x+120°)*sin(x-120°)=4根号3/3,(2cosxsin120°)/

x=0:0.1:2*pi;s=2*sin(x)-sin(2*x)+2/3*sin(3*x)-1/2*sin(4*x)+2/5*sin(5*x);plot(x,s)

前面步骤省略设:1sin(x)+2sin(2x)+…+nsin(nx)=sin[(n+1)x]/[4sin^2(x/2)]-(n+1)cos[(2n+1)x/2]/[2sin(x/2)]则需要sin[

∫1/sin⁴xdx=∫csc⁴xdx=∫csc²xd(-cotx)=-cotxcsc²x+∫cotxd(csc²x)=-cotxcsc²

sin^4x-sin^2xcos^2x+cos^4x=sin^4x+2sin^2xcos^2x+cos^4x-3sin^2xcos^2x=(sin^2x+cos^2x)^2-3sin^2xcos^2x

f(x)=(1+1/tanx)*(sinx)^2-2sin(x+π/2)sin(x-π/4)=(1+cosx/sinx)*(sinx)^2+2sin(x+π/4)cos[(x-π/4)+π/2]=(s

证明：∵cos²x-sin²x=cos2xcos⁴x+sin⁴x=1-2cos²xsin²x=1-(1-cos4x)/4=3/4+(co

2sinxcosx=sin2x那么sin^2xcos^2x=sin^22x/4另外sinx等价于x,所以sin^2x等价于x^2,也即x^2sin^2x变成了x^4不知您是否明白,若有不明还可问(⊙o

∫1/sin⁴xdx=∫csc⁴xdx=∫csc²xd(-cotx)=-∫(1+cot²x)d(cotx)=-(cotx+1/3*cot³x)+C

证明：因为左边=sin²X(sin²X+cos²X)+cos²X=sin²X+cos²X=1=右边,所以：(sinX)^4+sin²

∫sinxcosx/(1+sin^4x)dx=∫sinx/(1+sin^4x)d(sinx)=1/2*∫1/(1+(sin^2x)^2)d(sin^2x)=1/2*arctan(sin^2x)+C

sin^4x-sin^2xcos^2x+cos^4x=sin^4x+2sin^2xcos^2x+cos^4x-3sin^2xcos^2x=(sin^2x+cos^2x)^2-3sin^2xcos^2x