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Evan Tapper

Math Questions  - 
 
Happy Sunday, everyone.

I'm building a clockwork. I hope you might be able to please help with this puzzler.

I'd like the spokes in the black gears to align with the spokes in the white gears at the top of the hour. I'm close, but 1+1 ≠ 2.1 and I'd prefer to create a perfect equilateral triangle in the formation of the spokes if at all possible.

How much smaller does the white gear need to be? And how are you determining that solution? If a perfect equilateral triangle is geometrically impossible, keep black-to-white spoke alignment as a priority.

Thanks in advance.

P. S. I can't adjust the position of the black gears, given the rest of the design in the piece. 
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Mathematics

Challenges  - 
 
 
Can you count the pencils ??
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chandra singh's profile photoOladele Afolabi's profile photoKerem İnceçayır's profile photoMaurizio Taverna's profile photo
26 comments
 
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miel jodi

Communities  - 
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Tim Kamar's profile photoRahul Patil's profile photoYoel Brahms's profile photoSwami Arwin's profile photo
46 comments
 
+Paul Hartzer I agree with ypu ...
I made the correction ...
But your remark make me realize that i should  even not have made this post and the previous one too ...
What is done is done ... 
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Iwuchukwu Obieze

Math Questions  - 
 
I'm the special one!
What's ma name?!

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Serge Ribalchenko's profile photoSteve Simpson's profile photoSatchitanand Raghoonundun (Satchit)'s profile photoVicens Tort Arnau's profile photo
5 comments
 
1/2 of tau
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Rajan Gosavi

Videos/Pictures  - 
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Boro GROZDANIĆ's profile photoGerry Li's profile photoSatchitanand Raghoonundun (Satchit)'s profile photoc est moi je suis  moi's profile photo
6 comments
 
+Joanna Jimenez Thanks !!! Purposely we started with simple problem, just to revise some basic formulas of trigonometric & how to find out integration of the same !!! 
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pett Pette

Discussion  - 
 
Some things are impossible in all possible realities!
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Taeiolass T.'s profile photoArpita Chakraborty's profile photoASIT PAL's profile photo
52 comments
 
print("all positive integers")
; )
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Bruce Mincks

Discussion  - 
 
Pascal's Theorem

If a hexagon ab'ca'bc' is circumscribed to a conic, the straight lines p, q, r which join the three pairs of opposite sides are concurrent.

Branchion's Theorem

If a hexagon AB'CA'BC' is inscribed in a conic, the three pairs of opposite sides intersect one another in three collinear points, P, Q, R.

Luigi Cremona, Projective Geometry.  section 153.
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Bruce Mincks's profile photochuck grinnell's profile photoJyri Laumets's profile photoManuel Alzurutt's profile photo
3 comments
 
There is an excellent study of how Pappus of Alexandria reduced the problem of the duplication of the cube to the finding of two mean proportionals (along 2a = (a + c) + (a - c), I venture to imply):

Pappus of Alexandria and the Mathematics of Late Antiquity, by S Cuomo (Cambridge U, 2000)
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Best way to solve a math problem ever! 
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Sam's profile photoManuel Alzurutt's profile photo
Sam
 
imagination is key to any intelligence, without one can not see the problem.  
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Bruce Mincks

Discussion  - 
 
Primitve Concepts of Science
How many bits in a byte? At the end of Euclid's third book of theorems, about circles, Theorem 3-37 expresses an important, if arcane conclusion to the… - overhead lighting - Google+
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Kat Martin's profile photochuck grinnell's profile photoJyri Laumets's profile photoManuel Alzurutt's profile photo
6 comments
 
+Bruce Mincks Thank you .. I benefited.... I am Algerian and I speak Arabic and French and a little English
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About this community

Welcome to the Mathematics Community! Please read the community guidelines before posting: http://goo.gl/SjFp4. Here are the most import things you need to know: *Please check the Dr. Math FAQ if you've got a question that might be common. You might be posting about something that we've already seen numerous times. http://mathforum.org/dr.math/faq/ *Don't link-litter.* If you've found an interesting article that you think the Mathematics community needs to see, please share it! But we want to know why you think it's share-worthy. *No unrelated ads or spam.* *Don’t cheat on homework, classwork, or other exercises.* This community is not well-suited for homework help (see homework policy below), but it has zero tolerance for cheaters. Cheaters will be banned. *Categorize correctly.* *Keep posts relevant to mathematics in some way.* Wondering why your post was removed? Read the complete community guidelines.

nafiseh nafar

Discussion  - 
 
I want a pde (partial differential equation) for solving with dtm (differential transformation method).please help me.
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Brandon Conrady's profile photo
 
(I'm only commenting to see what people come up with)
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Do you think that there could possibly be a universal formula for any polynomial of any degree? It doesn't need to be in radicals.
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Infinite Flash Chess's profile photoKevin Burns's profile photo
7 comments
 
Check out the Durand–Kerner method on Wikipedia. It's not a formula, but an algorithm. I've written code to implement and it works quite well. 
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Henry Singer

Discussion  - 
 
Are bird murmurations examples of cellular automata?
As a video of a massive starling flock in motion goes viral, Wired Science takes a look at their seemingly reality-suspending tricks.
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Amadeo Artacho

Puzzles/Riddles  - 
 
Después de pasar un buen rato ojeando el blog matematicascercanas, R2-D2 ha empezado a hacer transformaciones de números realizando operaciones...
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Gato's profile photoAmadeo Artacho's profile photoc est moi je suis  moi's profile photoVicens Tort Arnau's profile photo
2 comments
 
+Gato The text says "has begun to make changes in numbers conducting operations "... "conducting operations" (haciendo operaciones)
Sorry for my bad English.
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Logisches Denken gefragt: Begründe jede Zahl logisch!
Logical thinking questioned: Justify each number logically!
It was a teaser, this Nr. 025:
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Matthias Urlichs's profile photoYehiamostafa Taha's profile photoc est moi je suis  moi's profile photoBaba 60's profile photo
5 comments
 
BITTE IST DAS EINE LOESUNGS METHODE
Die lineare gleichungen wie im Krammersmethode Matrizen und Determinanten oder was 
 ·  Translate
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Aegrotus Carnifex

Videos/Pictures  - 
 
Jim Overbeck's THE MADNESS OF MATHEMATICS. Overbeck created Non-Cantorian Set Theory, infinite sentences and transfinite fractions before specializing in Theosis in Greek Patristic Theology. He lives as a reclusive artist-intellectual in Italy.
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Roberto Santander's profile photoYoel Brahms's profile photoTim Kamar's profile photo
 
ok !
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Ramesh Chandra

Math Questions  - 
 
 2 minute mind refreshment ! :)
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vijay mohangekar's profile photoSatchitanand Raghoonundun (Satchit)'s profile photo
15 comments
 
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Kevin Clift

Puzzles/Riddles  - 
 
 
Chalkdust Crossnumber
set by Humbug

The winner of £100 and the answers to this crossnumber have just been announced in Chalkdust magazine, but there is nothing to stop you having a bit of fun before you read the solution!

Clues
Across

    1. D4 multiplied by D18. (10)
    5. A multiple of 101. (3)
    7. The difference between 10D and 11D. (10)
    9. A palindromic number containing at least one 0. (5)
    10. Subtract 24A multiplied by 24A backwards from 100000. (5)
    13. Subtract 8D from 35A then multiply by 17A. (5)
    15. Multiply this by 13D to get a perfect number. (2)
    16. The product of two primes. (2)
    17. A triangular number. (2)
    19. A factor of 6D. (3)
    20. 30A more than the largest number which cannot be written as the sum of distinct fourth powers. (7)
    22. The sum of seven consecutive primes. (3)
    23. When written in Roman numerals, this number is an anagram of XILXX. (2)
    24. The largest prime factor of 733626510400. (2)
    25. A square number. (2)
    27. The product of all the digits of 7A. (5)
    28. A multiple of 107. (5)
    30. Unix time at 01:29:41 (am) on 2 January 1970. (5)
    32. When written in a base other than 10, this number is 5331005655. (10)
    35. The smallest number which is one more than triple its reverse. (3)
    36. All but one of the digits of this number are the same. (10)

Down

    1. 700 less than 3D. (3)
    2. The sum of this number’s digits is equal to 16. (5)
    3. A Fibonacci number. (3)
    4. This is the same as another number in the crossnumber. (5)
    5. A square number containing every digit from 0 to 9 exactly once. (10)
    6. This number’s first digit tells you how many 0s are in this number, the second digit how many 1s, the third digit how many 2s, and so on. (10)
    8. The lowest prime larger than 25A. (2)
    10. The largest prime number with 10 digits. (10)
    11. A multiple of 396533. (10)
    12. If you write a 1 at the end of this number then it is three times larger than if you write a 1 at the start. (5)
    13. Multiply this by 15A to get a perfect number. (2)
    14. The factorial of 17D divided by the factorial of 16A. (7)
    17. The answer to the ultimate question of life, the universe and everything. (2)
    18. A multiple of 5. (5)
    21. The number of the D clue which has the answer 91199. (2)
    26. The total number of vertices in all the Platonic Solids (in 3D). (2)
    27. Two more than 29D. (5)
    29. The first and last digits of this number are equal. (5)
    31. A multiple of 24A. (2)
    33. Each digit of this number is a different non-zero square number. (3)
    34. A square number. (3)



More here: http://goo.gl/ePZi8p

Spoiler Alert (solution and winners)!: http://goo.gl/F1CqQZ

Chalkdust: http://goo.gl/8HPJPg

Image: http://goo.gl/FNpJZX
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Serge Ribalchenko's profile photoFederico Vera's profile photoAda Gil Ibáñez's profile photoVicens Tort Arnau's profile photo
2 comments
 
+Luke Jones
well symbols is just a symbols. It's humans who've been made this beautiful shapes look ugly.
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How many 6cm×4cm rectangles can fit in a circle that has an arc legnth of 546cm at 1/4 radians? 
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Muralikrishnan Ganapathy's profile photo
9 comments
 
On serious note: this is sector of circle with angle 1/4 radian right?
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Shamar Guishard

Challenges  - 
 
Heres a challenge for all of you mathematicians 
12 - 4 + 54 * 87 - (23 + 90)
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pizam yoyi's profile photoRuzica Imamovic's profile photoKarsten Uredat's profile photo
6 comments
 
4593
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