Problem with Expand[Expr, Trig ->True]
- To: mathgroup at smc.vnet.net
- Subject: [mg12705] Problem with Expand[Expr, Trig ->True]
- From: "S. Sankaranarayanan" <sankaras at egr.uri.edu>
- Date: Wed, 3 Jun 1998 02:20:57 -0400
- Organization: University of Rhode Island
- Sender: owner-wri-mathgroup at wolfram.com
Hi
I was trying to use Expand[Expr, Trig ->True] for an example given in
Mathematica book, second edition. It does not seem to work.
n[24]:= Expand[Sin[x]^2+Sin[2x]^2]
2 2
Out[24]= Sin[x] + Sin[2 x]
Expand[%,Trig ->True]
It gives likes this:
2 4 2 4
Cos[x] Cos[x] Sin[x] 2 2 Sin[x]
Out[25]= 1 - ------- - ------- + ------- + 3 Cos[x] Sin[x] - -------
2 2 2 2
But it is supposed to give
1 - Cos[2 x] - Cos[4 x]
-----------------------
2
But if I use
TrigReduce[Sin[x]^2 + Sin[2 x]^2]
It gives the needed answer.
2 - Cos[2 x] - Cos[4 x]
Out[23]= -----------------------
2
Responses will be very much appreciated.
Thanks,
Sankar