RE: Trigonometric simplification - newbe question

• To: mathgroup at smc.vnet.net
• Subject: [mg49031] RE: [mg49004] Trigonometric simplification - newbe question
• From: "David Park" <djmp at earthlink.net>
• Date: Tue, 29 Jun 2004 04:50:08 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Walter,

Add an assumption to Simplify (In Version 5, at least).

expr = (4*(2*a*Sin[(n*Pi)/2] - a*Sin[n*Pi]))/(n^2*Pi^2);

Simplify[expr, n \[Element] Integers]
(8*a*Sin[(n*Pi)/2])/(n^2*Pi^2)

But I don't know how one would specify in the assumptions that n was an even
integer greater than zero, say.

David Park

From: Christensen [mailto:fedderwi at uni-bremen.de]
To: mathgroup at smc.vnet.net

Hi,

this is a Mathematica newbe question for sure:

Mathematica comes up with the following result:

(4*(2*a*Sin[(n*Pi)/2] - a*Sin[n*Pi]))/(n^2*Pi^2)

Now I have the additional assumption that n is element of
{1,2,3, ...) (and a is real)

How do I tell Mathematica to take this into consideration and
remove the Sin[n*Pi] term?

Thanks,
Walter

Trigonometric simplification - newbe question

```

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