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Sorry but I cant figure this out, Someone gave me some help on here yesterday but they didn't show their working so I could not redo what they did when my equation changed.

Can someone please help me solve for X and show me the way that you do this please.


Thanks to anyone for any help they can give.


marked as duplicate by Dr. belisarius, Karsten 7., bbgodfrey, Yves Klett, Jens Mar 6 '15 at 19:09

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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    $\begingroup$ This site is for questions about Mathematica(TM), which is a software product. If you have questions about mathematics please post them in math.stackexchange.com $\endgroup$ – Dr. belisarius Mar 6 '15 at 15:11

eq = S == 360/(ArcCos[X/R]*2);Reduce[eq, X, Reals]

Out:R != 0 && S >= 180/[Pi] && X == R Cos[180/S]

or:Solve[eq, X, Reals]

{{X -> ConditionalExpression[R Cos[180/S], S >= 180/[Pi]]}}


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