Re: Trigonometric simplification

*To*: mathgroup at smc.vnet.net*Subject*: [mg68889] Re: [mg68838] Trigonometric simplification*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Tue, 22 Aug 2006 05:20:27 -0400 (EDT)*References*: <200608210727.DAA27449@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 21 Aug 2006, at 09:27, carlos at colorado.edu wrote: > As an intermediate result of some calculations I have > the expression > > r=Tan[a]^2/(Sec[a]^2)^(3/2) > > where a is real. How can I coerce Mathematica into > simplifying that to > > r=Cos[a]*Sin[a]^2 > > Both Simplify and FullSimplify with assumptions on a > fail to get the simpler form. > I would not be very happy if Mathematica did what you seem to want it to do only under the assumptions that a is real since: r = Tan[a]^2/(Sec[a]^2)^(3/2) Assuming[Pi/2 < a < 3*(Pi/2), Simplify[r]] (-Cos[a])*Sin[a]^2 On the other hand: Assuming[-Pi/2 < a < Pi/2, Simplify[r]] Cos[a]*Sin[a]^2 Andrzej Kozlowski

**Follow-Ups**:**Re: Re: Trigonometric simplification***From:*"Kai Gauer" <kai.g.gauer@gmail.com>

**References**:**Trigonometric simplification***From:*carlos@colorado.edu