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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)

[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

ǺͲʽ sin(x+h)-sinx=2cos(x +h/2)sinh/2 h0ʱlim[sin(x+h)-sinx]/h=lim2cos(x +h/2)sinh/2 /h ע⵽h0ʱlimcos(x +h/2)=cosx limsinh/2 /h=lim1/2 sinh/2 /(h/2)=1/2 lim[sin(x+h)-sinx]/h=cosx

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...

h(x)=cos2(x+/12)+1+2sin²x =cos(2x+/6)+1+1-cos2x =2+3/2cos2x-1/2sin2x-cos2x =2+(3-2)/2cos2x-1/2sin2x =2+(2-3)cos[2x+] =-arctan(2+3) Сڦ,Сֵ=2-(2-3), :(k+/2-, k+-), (k-, k+/2-) =-...

1У2{x|xkУ kZ} ⣺(1)Ϊf(x)cos( x)cos( x)( cosx sinx)( cosx sinx) cos 2 x sin 2 x cos2x f(x)СΪ У(2)h(x)f(x)g(x) cos2x sin2x cos(2x )2x 2k(k...

ʻҪ

¥,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,...

1gx+hx=sin2x+sinx+acosx٣g-x+h-x=sin2-x+sin-x+acos-x-gx+hx=sin2x-sinx+acosxڣ٢ڵhx=sin2x+acosxgx=sinx2hx=1-cos2x+acosx=-cosx-a22+a24+1a2Գa2...

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