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the Problem of Apollonius:Calculating (x,y,r) of eight circles given 3 circles
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Hi -
Is it possible to calculate the (x,y) co-ordinates and the radius of each of the eight circles, given three circles of known position and radius?
original 3 circles:
(ax1,ay1,ar1)
(ax2,ay2,ar2)
(ax3,ay3,ar3)
solutions:
(sx1,sy1,sr1)
(sx2,sy2,sr2)
etc
does it help to assume all 3 circles are in the 1st quadrant?... more »
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P2P Share files by email on Thu 04/25/2013
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Do you think that Peer-to-Peer, FTP
IRC technologies etc...are too much complicated !? There is a simpler technology to use, Autosend. This software allows file-sharing by only using your e-mail account. Autosend allows sharing files on your computer through regular email. It is an automatic file mailer... more »
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Card Magic and My Mathematical Discoveries
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Hi
I just published my first ebook titled “Card Magic and My Mathematical Discoveries” The book is an excellent mathematics resource for both performing art and implicit mathematics teaching. Moreover, the book is not only about card magic but it is also loaded with riddles, mathematical amusement and mind-blowing mathematical discoveries characterized by logical intelligence.... more »
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Math puzzle
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From high school days, some genuine recreational math:
A math professor was talking with his assistant.
"Yesterday I met three people," said the professor. "When you multiply their ages together, you get 2450. When you add their ages together, it adds up to twice your age. What are their ages?"... more »
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Children's Story Book to Introduce Set Theory, Order Theory
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My wife and I are having out first child and I'd like to make sure it is properly inundated with science and math as the backdrop for its life. I've been recently learning about set theory and order theory myself, and had the idea to introduce some of the basic concepts subtly through a children's story book. I'm reaching out to the folks on this list for ideas on how to do this.... more »
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primes in the arithmetic sequence 1, 31, 61, 91, 121, ... 30k+1 ...
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I was looking for a simple arithmetic sequence with
many primes "crowded together", i.e. quasi-consecutive ...
Suppose we let n = 1,097,495,500,000 ; then I get this:
n+19941 is prime, n+19971 is prime, n+20001 is prime,
n+20031 is prime, n+20061 is prime, n+20091 is prime,
n+20121 is composite,... more »
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Let's give away some goals
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[link]
Close packing. Geometry. Organizers of Brazil 2014 FIFA World Cup want to give away some official balls. We face a close-packing problem in order to know if we can fill Maracana stadium with enough balls to satisfy the Championship organizers' wishes.
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