<![CDATA[Math Is Fun Forum / Formulas]]> 2018-12-20T21:04:30Z FluxBB http://www.mathisfunforum.com/index.php <![CDATA[I am confused]]> I would say this means they are the same line and intersect everywhere.

Bob

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http://www.mathisfunforum.com/profile.php?id=67694 2018-12-20T21:04:30Z http://www.mathisfunforum.com/viewtopic.php?id=24712&action=new
<![CDATA[Tests For Divisibility]]> Here’s a YouTube video on tests of divisibility and how to apply them to some math problems.

I found the solution to finding all palindromic four-digit powers particularly interesting.

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http://www.mathisfunforum.com/profile.php?id=217821 2018-07-24T22:21:40Z http://www.mathisfunforum.com/viewtopic.php?id=13168&action=new
<![CDATA[Modern Algebra Symbols]]> Hi,

I have noticed that there are some symbols that are used in Modern (abstract) Algebra, that aren't necessarily listed in the math reference. "oplus", indicating a direct product between 2 groups, is one such example. I would like to track down a few others.
My most pressing need, is the sign for "is isomorphic to". (a tilde above an equal sign) How do I make this?

I didn't find the right solution from the Internet.

References:-
https://forum.openoffice.org/en/forum/viewtopic.php?f=12&t=93851

Thanks!

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http://www.mathisfunforum.com/profile.php?id=219202 2018-06-19T11:05:33Z http://www.mathisfunforum.com/viewtopic.php?id=24434&action=new
<![CDATA[Trigonometry Formulas]]> ganesh wrote:

(Angles are given in degrees, 90 degrees, 180 degrees etc.)

I.
Sin(-θ)=-Sinθ
Cos(-θ) = Cosθ
tan(-θ) = -tanθ
cot(-θ) = -cotθ
sec(-θ) = secθ
cosec(-θ)= - cosecθ

II.
sin(90-θ) = cosθ
cos(90-θ) = sinθ
tan(90-θ) = cotθ
cot(90-θ) = tanθ
sec(90-θ) = cosecθ
cosec(90-θ) = secθ

III.
sin(90+θ) = cosθ
cos(90+θ) = -sinθ
tan(90+θ) = -cotθ
cot(90+θ) = -tanθ
sec(90+θ) = -cosecθ
cosec(90+θ) = secθ

IV.
sin(180-θ) = sinθ
cos(180-θ) = -cosθ
tan(180-θ) = -tanθ
cot(180-θ) = cotθ
sec(180-θ) = -secθ
cosec(180-θ) = cosecθ

V.
sin(180+θ) = -sinθ
cos(180+θ) = -cosθ
tan(180+θ) = tanθ
cot(180+θ) = cotθ
sec(180+θ) = -secθ
cosec(180+θ) = -cosecθ

cot(180-θ)=-cotθ
since cot(180-θ)=1/tan(180-θ)

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http://www.mathisfunforum.com/profile.php?id=219080 2018-04-27T08:48:10Z http://www.mathisfunforum.com/viewtopic.php?id=3290&action=new
<![CDATA[Vector Formulas]]> ganesh wrote:

Where is the supposed "c" in the Left Hand Side?

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http://www.mathisfunforum.com/profile.php?id=212031 2018-01-27T07:09:29Z http://www.mathisfunforum.com/viewtopic.php?id=3289&action=new
<![CDATA[high school inequalities]]> All I can say is they are fundamental to any mathematical theory so can be taken as "unstated" axioms.  The quoted definition uses "OR", so is already using a logical symbol, and the logical symbols "AND" & "IMPLIES" are also used in the axioms.

Bob

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http://www.mathisfunforum.com/profile.php?id=67694 2017-06-16T14:02:14Z http://www.mathisfunforum.com/viewtopic.php?id=23956&action=new
<![CDATA[Homework help? Deriving an expression for the probability...]]> That page just leads me to a link with a bunch of gals in various stages of eating disorders...

Post when you are done and good luck.

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http://www.mathisfunforum.com/profile.php?id=33790 2017-03-12T08:16:31Z http://www.mathisfunforum.com/viewtopic.php?id=23781&action=new
<![CDATA[Discussions About The Formulas]]> Hi everyone, I have a formula in an Excel sheet which works fine to find the sum of two cells, (      =ABS(C26-D26)*100    ) which would have say 150.25 or 1.2609.However, although it shows the sum,

1   I would like a formula that would show the answer as either positive or negative depending whether the 2nd cell is lower or higher than the primary cell?

2   I would like the same in another cell to show the difference as a percentage + or -  ?

3   Also i would like to know a good place to learn more about Excell formula's?

Thanks

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http://www.mathisfunforum.com/profile.php?id=213423 2017-01-05T08:43:57Z http://www.mathisfunforum.com/viewtopic.php?id=3306&action=new
<![CDATA[A direct formula for HP]]> The blue area converges to Gamma.

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http://www.mathisfunforum.com/profile.php?id=95904 2016-12-27T04:46:33Z http://www.mathisfunforum.com/viewtopic.php?id=23624&action=new
<![CDATA[A simple converging series]]>
It converges only if

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http://www.mathisfunforum.com/profile.php?id=206089 2016-12-03T10:25:25Z http://www.mathisfunforum.com/viewtopic.php?id=23578&action=new
<![CDATA[Quartic formula]]> Nope

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http://www.mathisfunforum.com/profile.php?id=213230 2016-12-03T09:21:31Z http://www.mathisfunforum.com/viewtopic.php?id=18263&action=new
<![CDATA[Differential Calculus Formulas]]>
If
is a k-form of the form:

then we have a (k+1)-form
given by:

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http://www.mathisfunforum.com/profile.php?id=206089 2016-05-31T19:24:46Z http://www.mathisfunforum.com/viewtopic.php?id=3300&action=new
<![CDATA[Set Theory]]> I have been trying for a few days to understand this text of Zermelo, taken from his article of 1908 "Investigations in the Foundations of Set Theory", but I just do not seem to get it. I would really appreciate any help in deciphering it.
"13. Introduction of the product. If M is a set different from 0 and a is anyone of its elements, then according to No.5 it is definite whether M = {a} or not. It is therefore always definite whether a given set consists of a single element or not.
Now let T be a set whose elements, M, N, R, . . ., are various (mutually disjoint) sets, and let S1 be any subset of its union ST. Then it is definite for every element M of T whether the intersection [M, 8 1 ] consists of a single element or not. Thus all those elements of T that have exactly one element in common with 8 1 are the elements of a certain subset T 1 of T, and it is again definite whether T 1 = T or not. All subsets S1 of ST that have exactly one element in common with each element of T then are, according to Axiom III, the elements of a set P =  T, which, according to
Axioms III and IV, is a subset of union T and will be called the connection set [Verbindungsmenge] associated with T or the product of the sets M, N, R, . . .. If T = {M, N}, or T = {M, N, R}, we write T = MN, or T = MNR, respectively, for
short. "
I just do not understand why it is called "product" and how {M,N} can become MN here. Not in general therefore, but in this text. Thank you.

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http://www.mathisfunforum.com/profile.php?id=212335 2016-02-19T11:43:57Z http://www.mathisfunforum.com/viewtopic.php?id=3458&action=new
<![CDATA[Analytic Number Theory]]> Dirichlet Convolution

Let f, g be arithmetic functions. We define
by

for every natural number n. We call this function the Dirichlet convolution of f and g.

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http://www.mathisfunforum.com/profile.php?id=206089 2015-12-29T14:38:40Z http://www.mathisfunforum.com/viewtopic.php?id=22632&action=new
<![CDATA[trigo problem]]>

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http://www.mathisfunforum.com/profile.php?id=212090 2015-12-18T14:00:27Z http://www.mathisfunforum.com/viewtopic.php?id=22020&action=new