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[求助] 小女子公式求助，各位大神帮帮啦！已有3人参与

我有一个公式，需要求出x，s=2R*sin（x/2）+p*tan(x/2),各位大神这个该怎么求，谢啦！（s，R，p当做已知）

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哈哈

1楼 2016-01-21 09:57:08

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laosam280

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4楼2016-01-21 13:27:30

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【答案】应助回帖

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追风的风(Edstrayer代发): 金币+2 2016-01-24 03:37:32

Matlab 的solve命令!
例如!
>> solve('2*sin(x/2)+3*tan(x/2)=2','x')

ans =

[    2*atan((2/3*(-3/4+1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+1/4*((6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)-9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^3+(-3/4+1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+1/4*((6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)-9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^2-1)/(-3/4+1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+1/4*((6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)-9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2)))]
[ 2*atan((2/3*(-3/4+1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-1/4*((6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)-9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^3+(-3/4+1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-1/4*((6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)-9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^2-1)/(-3/4+1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-1/4*((6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)-9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2)))-2*pi]
[ 2*atan(2/3*(-3/4-1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+1/4*i*((-6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)+9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^3+(-3/4-1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+1/4*i*((-6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)+9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^2-1,-3/4-1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+1/4*i*((-6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)+9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))]
[ 2*atan(2/3*(-3/4-1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-1/4*i*((-6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)+9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^3+(-3/4-1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-1/4*i*((-6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)+9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))^2-1,-3/4-1/4*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)-1/4*i*((-6*(315+72*19^(1/2))^(1/3)*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)*(315+72*19^(1/2))^(2/3)+9*(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2)+48*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3)/(((315+72*19^(1/2))^(2/3)+9+3*(315+72*19^(1/2))^(1/3))/(315+72*19^(1/2))^(1/3))^(1/2))^(1/2))]

>> double(ans)

ans =

0.7824
  -4.5525
5.0266 - 2.6622i
5.0266 + 2.6622i

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善恶到头终有报,人间正道是沧桑.

2楼2016-01-21 10:20:33

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

liuqh

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【答案】应助回帖

★
感谢参与，应助指数 +1
追风的风(Edstrayer代发): 金币+1 2016-01-24 03:37:43

将sin(x/2)用tan(x/2)表示后，化简可得一个四次方程，有解析解

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3楼2016-01-21 10:38:24

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引用回帖:

2楼: Originally posted by wurongjun at 2016-01-21 10:20:33
Matlab 的solve命令!
例如!
>> solve('2*sin(x/2)+3*tan(x/2)=2','x')

ans =

>> double(ans)

ans =

0.7824
-4.5525
5.0266 - 2.6622i
5 ...

可不可以结果出现R,s,p啊