1-2sin²3x
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两边平方得sin²x/2-2sinx/2cosx/2+cos²x/2=1/91-sinx=1/9sinx=8/9
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-
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[
tan²-1=sin²x/cos²x-1=(sin²x-cos²x)/cos²x=(sinx+cosx)(sinx-cosx)/cos&su
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
sin(x+π/6)=1/3sin(5π/6-x)=sin[π-(x+π/6)]=1/3sin^2(π/3-x)=sin^2[π/2-(x+π/6)]=cos^2(x+π/6)=1-sin^2(x+π
由和差化积公式分子=2sin[(x^3+x^2)/2]cos[(x^3+x^2-2x)/2]x→0,则(x^3+x^2)/2→0,sin则(x^3+x^2)/2和(x^3+x^2)/2是等价无穷小而c
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)
cos(3x)-sin(3x)=cos(2x+x)-sin(2x+x)=cos2xcosx-sin2xsinx-sin2xcosx-cos2xsinx=(cos^2x-sin^2x)cosx-2sin
sin^2x+cos^2y=1/2∴sin^2x=1/2-cos^2y3sin^2x+sin^2y=3(1/2-cos^2y)+sin^2y=1.5-3cos^2y)+sin^2y又有sin^2y+c
f(x)=(√3/2)sin2x-(1/2)[(cosx)^2-(sinx)^2]-1=(√3/2)sin2x-(1/2)cos2x-1=sin(2x-π/6)-1f(x)的最大值是0,最小值是-2,
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
3/2cosx-3/2(sinx)^2
2(√3/2sinx+1/2cosx)=2sin(x+π/6)√2*√2(√2/2sinx-√2/2cosx)=2sin(x-π/4)(3)解;2√2(1/2cosx-√3/2sinx)=2√2cos
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
3次分部积分法解用!代表积分号=!(x^3-x+1)(1-cos2x)/2dx=(x^3-x+1)(x/2-sin2x/4)-!(3x^2-1)(x/2-sin2x/4)dx+c=-!(3x^2-1)