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ǰλãҳ >> ΪʲôCos(x+h)%Cosx=%2sin(x+h/2)sin(h/2) >>

ΪʲôCos(x+h)%Cosx=%2sin(x+h/2)sin(h/2)

Ͳʽ Уa=x+hb=x

sin(x+h)-sinx=sinxcosh+sinhcosx-sinx=sinx(1-2sin²h/2)+2sin(h/2)cos(h/2)cosx-sinx=-2sinxsin²(h/2)+2sin(h/2)cos(h/2)cosx=2sin(h/2)[cos(h/2)cosx-sin(h/2)sinx)=2cos(x+h/2)sin(h/2)

Ϊcos(x+h)-cosx=-2sin(x+h/2)sin(h/2) :lim [cos(x+h)-cosx]/h =lim[-2sin(x+h/2)sin(h/2)/h] =lim[-sin(x+h/2)sin(h/2)/(h/2)] =lim[-sin(x+h/2)] =-sinx

Ϊд,涼ʡԵlim(h0) cosxĶ(-,+),cosxcos(x+h)ж [cos(x+h)-cosx]/h =-2sin[(x+h+x)/2]sin[(x+h-x)/2]/h =-sin[(2x+h)/2]*sin(h/2)/(h/2) =-sinx*1 =-sinx

ע⣬ûֱ֤ȿ sin(x+h)-sinx = sinxcosh+cosxsinh-sinx = sinx(cosh-1)+cosxsinh = 2cosxsin(h/2)cos(h/2)-2sinxsin^2(h/2) = 2sin(h/2){cosxcos(h/2)-sinxsin(h/2)} = 2sin(h/2)cos(x+h/2) = 2cos(x+h/2)sinh/2 sinx+...

[cos(x)]'=lim{[cos(x+h)-cos(x)]/h} =lim{(1/h)[-2sin(x+h/2)sin(h/2)]} Ͳ =lim{-sin(x+h/2)*[sin(h/2)/(h/2)]} һҪ:lim(x0)[sin(x)/x]=1 =-sinx

ǺĺͲʽ:sinx-siny=2cos[(x+y)/2]sin[(x-y)/2] ɵsin(x+h)-sinx=2cos[(x+h+x)/2]sin[(x+h-x)/2]=2cos...

1ߺfx=sinx+գأ00գУΪУ= 2 T =2y=fxһԳΪ ( 4 0) աʣ0Уf 4 =sin2 4 +գ=0æ= 2 fx=cos2xfxͼеĺ쳤...

¥,Ƶ򷨵ĸ. ĿѼӺ©: x(t)=0.5*cos10t+0.2cos(100t-45);H(s)=1/(0.005s+1) ָ,ϵͳпԵӵ,˲ֽ r1(t)=0.5cos10t;r2(t)=0.2cos(100t-45) Ƶָ:ϵͳ,...

function [Y] = RK45(t,X,f,h) K1=f(t,X); K2=f(t+h/2,X+h/2*K1); K3=f(t+h/2,X+h/2*K2); K4=f(t+h,X+h*K3); Y=X+h/6*(K1+2*K2+2*K3+K4); end 4Ĵ: ԼдΪf.m function dxdt = f (t,x) dxdt(1)=exp(x(1)*sin(t)...

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