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Conferences  The CTK Exchange College math |
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Discussion Topic |
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Last Updated Date/Author |
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discrete math
axiam 1: every line is a set of points.
axiam 2: for each line 'L' there is a point on 'L'.
axiam 3: there exists at least 2 points.... |
zain  |
Jan-26-11 02:33 PM
by zain |
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Math proof that sphere has max volume to surface area
I am working with a physician friend on a problem (we're both in our 50's and our math is pretty rusty) - and was trying to find proof that th... |
dscharpi1 |
Jan-22-11 11:23 AM
by alexb |
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Regular Polygon problem
In doing some experimental drawing in AutoCAD I ran across what appear to be some interesting relations that appear to be true but which I am unable t... |
Jeremy Dunn |
Jan-20-11 08:44 AM
by alexb |
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Creating a formula
Hi there i saw your post about "Maximum Volume of a Cut Off Box" (http://www.cut-the-knot.org/Curriculum/Calculus/BoxVolume.shtml)... |
Anthroxy |
Jan-15-11 11:56 AM
by alexb |
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Please help!
A friend of mine created a puzzle that I cannot solve, but it somehow relates to Pi.
A = , B = , C = , D = , E =
F ... |
hdk |
Dec-14-10 07:35 AM
by hdk |
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glaring apportionment error
Your apportionment computations have an error, in that they ignore the fact that the lower quota is never less than one. According to your site, ... |
Haim Zamir |
Nov-11-10 09:44 AM
by alexb |
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doll house window
HexyPexy
Hi - visited a quilter friend the other eve, and saw the dollhouse being worked on. There were two windows, each with same design,... |
HexyPexy |
Oct-27-10 11:28 PM
by alexb |
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4 Travellers problem
Hello Alex,
Ca fait longtemps...
I read the solution to 4 travellers by S. Anderson and the
conclusion that they... |
Maj. Pestich |
Oct-04-10 01:39 PM
by HART32Cora |
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Concentric Circles In Crossing Circles
Two circles (O1), (O2) intersect each other at A, B. Two circles (Oa), (Ob) centered at any point O: (Oa) passing A, (... |
Bui Quang Tuan |
Sep-23-10 07:33 PM
by alexb |
16
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Concurrency With Six Touching Circles
Dear All My Friends,
Given six circles (C1), C(2), ... (C6) external touching as following:
(C1) and C(2) are touch... |
Bui Quang Tuan |
Sep-09-10 10:26 AM
by mpdlc |
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Broken Chord And Pythagorean Theorems
Dear All My Friends,
The Broken Chord Theorem is one of very small interesting theorems which credited to Archimedes. There are some proofs for... |
Bui Quang Tuan |
Aug-26-10 10:31 AM
by alexb |
3
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Three Right Triangle Construction Problems
Dear All My Friends,
To construct triangle ABC right at C such that altitude length from C is maximal, in three cases:
1. Given a + b
2.... |
Bui Quang Tuan |
Aug-21-10 05:41 AM
by mpdlc |
4
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Fermat Point
I don't understand the second solution for finding the Fermat point P of a triangle (P is defined to be the point minimizing the sum AP + BP +... |
Owen |
Aug-07-10 04:26 PM
by Owen |
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Areas Of Two Special Triangles And Pythagorean Theorem
Dear All My Friends,
Please try one interesting problem: first prove following small lemma then use the lemma to prove Pythagorean theorem!... |
Bui Quang Tuan |
Aug-06-10 08:28 AM
by Bui Quang Tuan |
7
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Cyclic Touching Circles Around Triangle
[View All]
Dear All My Friends,
In the triangle ABC we select one direction, say A to B to C to A to B...
At vertex A: construct a circle (A1) ... |
Bui Quang Tuan |
Jul-30-10 05:15 PM
by mpdlc |
21
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H. Eves' Tricky Quickie In N-Gon
Dear Alex,
Other than triangle, H. Eves' tricky quickie can be used for n gon. I recommend one better geometric inlustration for following ... |
Bui Quang Tuan |
Jul-29-10 06:35 AM
by alexb |
1
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MinMax inequality
On the website http://www.cut-the-knot.org/arithmetic/MinMax.shtml
the min-max inequality is shown. However, I think that the proof of t... |
PeterB |
Jul-22-10 03:28 PM
by alexb |
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Probability
A radio station asks for a caller of a specific year to call. Then the station then spins a "month" wheel for the caller to win a prize if their b... |
MikeS |
Jul-11-10 07:50 PM
by alexb |
8
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how do I solve this trigonometric equations system?
Hello:
I am trying to solve this system:
A*cos(x) + B*sin(y) = C
D*sin(x) + E*cos(y) = F
I have t... |
Manuel Sandoval |
Jul-10-10 06:58 AM
by Gerenuk |
2
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Novel Square Triangular Nos. Generalization?
Certain triangular numbers are also square numbers: e.g. T(8) = 36 = 6^2, T(49) = 1225 = 35^2. It is well known that the argum... |
Kenneth Ramsey |
Jun-28-10 07:14 AM
by alexb |
1
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Vertex Next Side Midpoint Quadrilateral
Dear All My Friends,
Given convex quadrilateral X1X2X3X4.
Y1, Y2, Y3, Y4 are midpoints of sides X1X2, X2X3, X3X4, X4X1 respect... |
Bui Quang Tuan |
Jun-08-10 01:29 PM
by Bui Quang Tuan |
15
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Vector Sum
The following seems obvious, but how do you prove it?
The sum of the n vectors that start at the center of a regular n-gon and end at a verte... |
Bractals |
May-31-10 06:15 PM
by alexb |
1
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infinite probability
hi i am having trouble with the following question, wondering if someone can help me, thanks in advance
Q. if i have a very large number of p... |
girl_honey |
May-22-10 10:12 PM
by girl_honey |
2
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Compass Alone Constructions
On the page "Geometric Construction with Compass Alone" can the constructions be done with a collapsible compass? ... |
Bractals |
May-04-10 12:31 PM
by alexb |
1
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Probability/Stats question
Suppose that I sample from some unknown continuous distribution. I know that the draws are iid, but the distribution itself is unknown. However, I... |
Ralphbne |
Mar-17-10 08:02 PM
by alexb |
1
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Acute angled triangles
If an acute angled triangle has sides of length x, y and z, where x<=y<=z, show that the corresponding angles, X, Y, and Z, can ... |
johnm_12 |
Mar-11-10 06:26 PM
by alexb |
3
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Strange question in probability....
Suppose 1/2 0. Let sigma=bet/(1-delta).
Let x0=sigma/2.
With probability 1/2, x_(k+1)=min(x/delta, sigma)... |
Ralphbne |
Feb-15-10 00:43 AM
by alexb |
1
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Probability
The question that I am faced with, and am apparently way over my head with is: given a spinner numbered 1-10 and assuming that this spinner will ... |
Travis |
Jan-27-10 09:48 PM
by Travis |
2
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Impossible right triangle?, newzad's theorem
Hi Alexander,
Your web site is great.
My problem is I want to know that is this right triangle possible?
http://i47.tinypic.com%... |
newzad |
Jan-03-10 00:39 AM
by newzad |
0
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tractrix
I have a question about the tractrix curve.
The pseudosphere or tractroid surface, the surface of revolution based on the tractrix, is suppo... |
alan b |
Oct-26-09 07:26 AM
by alexb |
1
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