#math - Sun 25 Mar 2007 between 00:05 and 00:27

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fulldmbot: Solve[x==2]
centrxit's %
% Solve[x==2]
mbotcentrx: {{x -> 2}}
kmhmy brain hurts <----- monty python
fulldnice
aidan[c(az-b)] / [e(az+1)] == 0
fulld% Solve[x==sin(72)]
mbotfulld:
Solve::svars: Equations may not give solutions for all "solve" variables.
{{sin -> x/72}}
aidanwhat can I do with that? I need to find an approximate expression for z
fulldaidan: if c==0, it could be anything
aidanaz is a little more complicated than az
fulldif (az-b)==0
then z= b/a
aidanah, so I can let both the bottom half and the top half == 0?
fulldno, you can let either factor of the top == 0
aidanah, of course ... gosh my fundamentals are shocking
fulldI'd like to find the exact cosine of 72, 360/7, and 40 as an algrbraic expression. Are any of those possible?
aidanso if I let c = 0, I get a trivial solution?
fulldaidan: yes
Kasadkad``fulld: yes
(also if you're using degrees, specify, since everyone uses radians)
john_sheufulld: taylor series?
fulldKasadkad``: yes these are degrees, sorry about that
Kasadkad``fulld: At least I'm pretty sure it's possible to express those in terms of radicals
fulldI that that for some arguments, mathematica magically knows the answer -- but I'm too poor for that
what techniques should I use to simplify the taylor series?
Kasadkad``Taylor series?
fulldooh, radicals could be good
Kasadkad``I don't think the Taylor series will help you
john_sheudoes Mathematica count as a "technique"?
fulldjohn_sheu: i wish i could
Kasadkad``: if there anything other than basic trig identites I can use to put it in a radical form?
Kasadkad``fulld: The brute force way to do it is to write cos(nx) as a polynomial in cos(x)
fulldKasadkad``: is that Chebyshev polynomial?
Kasadkad``e.g. cos(5x) = p(cos(x)) where p is a polynomial, and then p(cos(72)) = cos(360) = 1, so if you can solve that polynomial you're done
Yeah
fulldcool, I reading the wiki now

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