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Simplify for ca^2+sa^2==1

• To: mathgroup at smc.vnet.net
• Subject: [mg26339] Simplify for ca^2+sa^2==1
• From: Adalbert Hanssen <hanssen at Zeiss.de>
• Date: Tue, 12 Dec 2000 02:54:50 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi, MathGroup,

in a lengthy expression, I know, a lot
of simplification can be done, if Simplify
and the like would take into account that
for varaibles ca and sa

ca^2+sa^2==1

I know, that I can set ca=Sqrt[1-sa^2] and
deal with the branch cut by hand.

The bad thing is, that these ca^2 and sa^2
are expanded out in lenghty subexpressions
involving lots of other symbols. So far, I
have found no way (but would be glad, if 
someone could advise me one), to factor out
(ca^2+sa^2). 

Unfortunately, there are also terms, where 
(1+ca^2+sa^2) or (2*ca^2+2*sa^2) can be 
factored out, also others with (-ca^2-sa^2) 
and so on.

Any general tip, how to best cope with such
algebraic manipulations?


kind regards

Dipl.-Math. Adalbert Hanszen

• Follow-Ups:
  • Re: Simplify for ca^2+sa^2==1
    • From: "Carl K. Woll" <carlw@u.washington.edu>