sin(a-b)=3/5,cos(a+b)=5/13且a b都是锐角求cos2a和cos2b
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/25 21:17:42
![sin(a-b)=3/5,cos(a+b)=5/13且a b都是锐角求cos2a和cos2b](/uploads/image/z/1041030-54-0.jpg?t=sin%28a-b%29%3D3%2F5%2Ccos%28a%2Bb%29%3D5%2F13%E4%B8%94a+b%E9%83%BD%E6%98%AF%E9%94%90%E8%A7%92%E6%B1%82cos2a%E5%92%8Ccos2b)
xRJ@L:Lf#0M
n*(HB܋KZvDUpΙsʢ:GXg";:"\4[
[}_3f5_(zeDHH+pp%iGd?>z(M,lg!(m%n̳&1iq#38I<Q`7Fwk5XO#G Qf\T,Ͻ֟$ ]I>b_{r.}ȩ.
sin(a-b)=3/5,cos(a+b)=5/13且a b都是锐角求cos2a和cos2b
sin(a-b)=3/5,cos(a+b)=5/13且a b都是锐角求cos2a和cos2b
sin(a-b)=3/5,cos(a+b)=5/13且a b都是锐角求cos2a和cos2b
a b都是锐角
即0-π/2
cos(a-b)=√[1-(sin(a-b))^2]=4/5
sin(a+b)=√[1-(cos(a+b))^2]=12/13
cos2a=cos(a+b+a-b)
=cos(a+b)cos(a-b)-sin(a+b)sin(a-b)
=5/13*4/5-12/13*3/5
=-16/65
cos2b=cos(a+b-(a-b))
=cos(a+b)cos(a-b)+sin(a+b)sin(a-b)
=5/13*4/5+12/13*3/5
=56/65
∵a b都是锐角
sin(a-b)=3/5
cos(a-b)=4/5
cos(a+b)=5/13
sin(a+b)=12/13
cos2a=cos(a+b+a-b)
=cos(a+b)cos(a-b)-sin(a+b)sin(a-b)
=5/13*4/5-12/13*3/5
=-16/65
cos2b=cos(a+b-(a-b))
=cos(a+b)cos(a-b)+sin(a+b)sin(a-b)
=5/13*4/5+12/13*3/5
=56/65
cos(a+b)cos(a-b)+sin(a+b)sin(a-b)=-3/5,求sin(3π/2+2b)
sin(a-b)*cos a-cos(a-b)*sin a=1/5,则cos 2b的值是
当a=3π/4时,sin(a+b)+cos(a+b)+sin(a-b)+cos(a-b)
由cos(a+b)=cos a cos b-sin a sin b cos(a-b)=cos a cos b+sin a sin b解题设a为锐角,证:1、2分之根3乘cos a + 2分之1乘sin a=cos(6分之π-a)2、cos a-sin a=根号2cos(4分之π+a)
Cos(a+b)*cos(a-b)=1/5 求cos ^2-sin^2
【(sin a+cos a)/(sin a-cos a) 】=3,tan (a-b)=2,tan (b-2a)=?
如何证明sin(a+b)=sin(a)cos(b)+cos(α)sin(b)
cos(a+b)cos(a-b)-sin(a+b)sin(a-b)=3/5,则sina=
已知tana,tanb 是方程x^2-5x+6=0的两个实数跟求2sin^2(a+b)-3sin(a-b)cos(a+b)+cos^2(a+B)+cos^2(a+b)的值求2sin^2(a+b)-3sin(a+b)cos(a+b)+cos^2(a+B)的值
sin(a+b)cosa-cos(a+b)sina=5/13 则sin(π-B)=?
cos(a-b)cos(b-c)+sin(a-b)sin(b-c)=
已知 sin a +sin b =1/4cos a +cos b =1/3求 tan (a+b)
已知sin(a+b)sin(a-b)=-1/3,求cos^2a-cos^2b的值
cos^2a-cos^2b=m,那么sin(a+b)sin(a-b)=?
cos²a-cos²b=c,则sin(a+b)sin(a-b)=
cos∧a-cos∧b=t则sin(a+b)sin(a-b)=
证明sin(A+B)sin(A-B)=cos^2B-cos^2A
已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值第一题1/2cos x-√3/2sin x第二题√3sin x+cos x第三题√2[sin x-cos x]第四题√2cos x-√6sin x