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Re: Simplification question in Mathematica 7

  • To: mathgroup at smc.vnet.net
  • Subject: [mg113855] Re: Simplification question in Mathematica 7
  • From: Barrie Stokes <Barrie.Stokes at newcastle.edu.au>
  • Date: Tue, 16 Nov 2010 05:04:10 -0500 (EST)

 Jennifer:

You will find that

Sqrt[-(((ea - eb)^2 + (na - nb)^2)*(-mb1^2 - mb2^2 + mb2^2*Cos[2*b1] + 
 mb1^2*Cos[2*b2])*Csc[b1 + b2]^4)]/Sqrt[2] // TrigExpand // Simplify

will get you what you want, perhaps?

HTH

BArrie

>>> On 15/11/2010 at 9:50 pm, in message <201011151050.FAA09230 at smc.vnet.net>,
Jennifer Hatz <btjunkie.org at abv.bg> wrote:
> Both FullSimplify and Simplify do nothing on the following expression
> Sqrt[-(((ea - eb)^2 + (na - nb)^2)*(-mb1^2 - mb2^2 + mb2^2*Cos[2*b1] + 
> mb1^2*Cos[2*b2])*Csc[b1 + b2]^4)]/Sqrt[2]
> 
> I found out that it is possible to further simplify it to
> Sqrt[((ea - eb)^2 + (na - nb)^2)*Csc[b1 + b2]^4*(mb2^2*Sin[b1]^2 + 
> mb1^2*Sin[b2]^2)]
> 
> as
> FullSimplify[Sqrt[(-(ea - eb)^2 - (na - nb)^2)*(-mb1^2 - mb2^2 + mb2^2*Cos[2*b1] + 
> mb1^2*Cos[2*b2])*Csc[b1 + b2]^4]/Sqrt[2] - Sqrt[((ea - eb)^2 + (na - 
> nb)^2)*Csc[b1 + b2]^4*(mb2^2*Sin[b1]^2 + mb1^2*Sin[b2]^2)]]
> produces zero
> 
> The question is - is it somehow possible to tell mathematica to convert the 
> first expression into the second?
> Are there any additional commands that work on trigonometric functions 
> better than Simplify?
> 
> Thanks in advance



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