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RE: Inverse Tangent function

• To: mathgroup at smc.vnet.net
• Subject: [mg80012] RE: [mg79970] Inverse Tangent function
• From: "Jaccard Florian" <Florian.Jaccard at he-arc.ch>
• Date: Fri, 10 Aug 2007 06:40:28 -0400 (EDT)
• References: <200708100538.BAA10433@smc.vnet.net>

Is this what you want ?

In[31]:= w1 = ArcTan[x]; w2 = ArcTan[y];
Simplify[TrigExpand[Tan[w2 - w1]]]

Out[32]= (y - x)/(x*y + 1)

  
Florian Jaccard



-----Message d'origine-----
De=A0: Boen S. Liong [mailto:mr_bean_curdy at yahoo.com]
Envoy=E9=A0: vendredi, 10. ao=FBt 2007 07:38
=C0=A0: mathgroup at smc.vnet.net
Objet=A0: [mg79970] Inverse Tangent function

Please help:

Let w1 = tan-1(x)  i.e. inverse tangent of x or tan(w1) = x

w2 = tan-1(y)  i.e. tan(y) = w2

and w3 = w2- w1

problem: find tan(w3) in term of x and y.

or better yet:

let x= x1/z1

and y= y1/z1

problem:find tan(w3) in term of x and y.

I know the formula for tan( u+v) or tan(u-v). but please help for the
above. thank you.

Boen S. Liong

• References:
  • Inverse Tangent function
    • From: "Boen S. Liong" <mr_bean_curdy@yahoo.com>