Re: Re: Exact value of Cos[Pi/17]
- To: mathgroup at smc.vnet.net
- Subject: [mg14876] Re: [mg14851] Re: Exact value of Cos[Pi/17]
- From: BobHanlon at aol.com
- Date: Mon, 23 Nov 1998 10:11:54 -0500
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 11/20/98 5:07:48 AM, hay at haystack.demon.co.uk writes: >Christopher Gorski wrote in message <72tt9f$isg at smc.vnet.net>... >>In The Mathematica Book, there is an example on page 936 of Mathematica >>returning the exact answer to Cos[Pi/17]. When I try it out on my NT >>machine, however, (mathematica v.3), it simply returns Cos[Pi/17]. >>I've searched throughout the book, and I can't figure out how to get my >>system to return a answer as in the example given. It will return >>simple things, Cos[Pi], for example, returns -1, but more complex >>arguments won't work. >> >>-- >>Christopher Gorski >>cgorski at adelphia.net >>http://www.contrib.andrew.cmu.edu/~cgorski >> >> >> > >Christopher (using InputForm for Output cells) > >Cos[Pi/17] > >Cos[Pi/17] > >FunctionExpand[%] > >1/4*Sqrt[1/2*(15 + Sqrt[17] + Sqrt[2*(17 - Sqrt[17])] + > Sqrt[2*(34 + 6*Sqrt[17] - Sqrt[2*(17 - Sqrt[17])] + > Sqrt[34*(17 - Sqrt[17])] - > 8*Sqrt[2*(17 + Sqrt[17])])])] > Allan, FunctionExpand does not do this on my system: $Version "Power Macintosh 3.0 (May 6, 1997)" Cos[Pi/17] Cos[Pi/17] FunctionExpand[%] Cos[Pi/17] Bob Hanlon