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Conferences  The CTK Exchange High school |
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Discussion Topic |
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Last Updated Date/Author |
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ABC triangle
ABC triangle BD bisects ∠ABC, D on AC, m∠ABC =80 , AD=BD+BC find m∠C... |
Anderson derty  |
Jul-24-11 03:04 PM
by alexb |
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Pigeonhole Principle Qn 43 - an error?
'Prove that no seven distinct positive integers, not exceeding 24, can have sums of all subsets different.'
I think the solution given is... |
Bernard Murphy |
Apr-21-11 10:49 AM
by alexb |
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Number theory question
The Problem:
Suppose for a positive integer n both 5n+1 and 7n+1 are perfect squares. Show that n is divisible by 24
My attempt:
Sin... |
shivgaur |
Apr-07-11 11:54 AM
by mr_homm |
5
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Number Theory Problem
The question is:
Show that there are positive integers m and n, with m > n, such that 2^m – 2^n is a multiple of 2011.
You do not... |
shivgaur |
Mar-13-11 03:56 PM
by shivgaur |
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Schwarz Lantern
Does someone know of an applet that displays the Schwarz lantern (or pineapple) and computes the surface area, let's say with sliders for a ra... |
danieladaniela |
Mar-12-11 06:40 PM
by alexb |
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inequation
hi,
would anyone kindly suggest a method for solving this inequation?
Find all real numbers such that:
x^4-3x^3-x^2-x-2 is ... |
abhi |
Feb-25-11 09:33 AM
by abhi |
2
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10 digits add to 100
Hi everyone,
I am not sure if i am plane stupid,( probably am) or this is big Math..
This is the problem:
Use all digits 0-9 onc... |
huntermykey |
Feb-23-11 02:05 PM
by alexb |
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Digitla Roots
Digital Root of a Product
On the page
http://www.cut-the-knot.org/arithmetic/rapid/defensive.shtml
Alexander casually state... |
Sandy |
Feb-15-11 04:29 PM
by alexb |
1
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a generalized version of PT
http://www.tsiros.net/pyth/yapt.JPG
ABC: a right triangle
M: a point
Prove that A1+A2=A3 or that areas with same colo... |
P.Tsiros |
Jan-24-11 00:13 AM
by alexb |
12
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Probablities section on cut the knot site
I am having difficulty understanding how they explain probablities using sets or union and intersection. I get lost soon after they begin talking abou... |
Andrew Touchet |
Jan-18-11 09:10 AM
by alexb |
1
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Four numbers equal 24?
Using 5, 5, 5, and 1 ONLY adding subtracting, multiplying and dividing is it possible to get those four numbers to equal 24 and if so how?%0... |
Rose |
Jan-13-11 09:06 PM
by alexb |
18
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drawing puzzle
[View All]
My third grade math teacher gave us a drawing puzzle I'm still trying to solve thirty odd years later. Now my daughter's trying to figure it out a... |
martin gran |
Dec-06-10 11:32 PM
by David W. |
34
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trajectories on the torus
First of all, let me thank Prof. Bogomolny for this marvelous and ever-growing site.
I hope may be some reader can help me find an applet I saw s... |
danieladaniela |
Nov-19-10 08:52 AM
by Daniela |
5
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Would someone comment on the soundness of this statement?
I have tried to simplify the teaching of relationships of inverse functions' derivatives by using a term I created called "counterpoints." So i... |
jmolokach |
Sep-30-10 07:35 AM
by alexb |
9
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Golden Ratio in Algebra
Looking to find original article referenced in CTK entitled "Golden Bounds for the Roots of Quadratic Equations". Supposedly published by the Math... |
janco |
Sep-14-10 10:26 PM
by mr_homm |
11
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Geometry
Length of an angle bisector in terms of AC ,AB , BC... |
k.p. |
May-17-10 06:39 AM
by alexb |
1
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saa triangle construction
how do we construct triangle when 1side and 2 angles are given, such that the side is not included between those angles?... |
rahul_khs |
May-02-10 09:45 PM
by alexb |
5
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Proof number 27
I want to understand proof number 27 in the amazing list of pythagorean theorem proofs. But unlike some of the other proofs this proof doesn't expla... |
Teja Ravivarapu |
Apr-29-10 07:58 PM
by alexb |
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A property of equilateral triangles
This is a very beautiful property of equilateral triangles.
Let ABC an equilateral triangle, and M any point inside it. Divide the triangle in six... |
mffsilva61 |
Apr-08-10 11:41 AM
by alexb |
1
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finding volume of a tetrahedron
Is there a formula for finding the volume of a tetrahedron? I looked through the geometry listings, but I didn't find anything about tetrahedron... |
Nina |
Mar-21-10 11:22 PM
by alexb |
1
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proof 13
who came up with proof 13 for the pyageran them.... |
that guy |
Mar-17-10 08:53 PM
by alexb |
1
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Random Riddle
A typical example of a random sequence of 0s and 1s (of length n, say) is one that is obtained by repeated tossings of a fair coin, with "he... |
Arturo |
Oct-16-09 03:47 PM
by alexb |
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Construction in Geometry
How would I construct
(A) an isosceles triangle if only given the altitude to the base and a base angle?
(B) an isosceles trapezoid ... |
nicoleg |
May-22-09 11:00 AM
by alexb |
1
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Transformations & coordinate plane
This is a question about terminology and/or syntax.Can someone out there please explain to me why when describing reflections over a particular ax... |
csilva85 |
Apr-09-09 02:16 PM
by alexb |
1
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Monge via Desargues
My math teacher challenged me to prove to him why the lines formed by the tangents are collinear. I showed him the proof off of cut the knot(http:... |
Don Johnson |
Apr-09-09 02:10 PM
by alexb |
1
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Monge via Desargues
My Math teacher was challenging me to prove how the tangents formed by the circles are collinear and when I showed him the proof off of cut-the-knot%2... |
Don Johnson |
Apr-07-09 09:23 PM
by alexb |
1
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sum of squares
can anyone find a proof for 1^2+2^2+...+n^2=n(n+1)(2n+1)/6 without using induction?... |
Andrew M |
Apr-05-09 06:59 AM
by robert king |
10
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product of fractions
Hi
In a book on sequences, there's this product:
(1 - 1/4 ) · (1 - 1/9) · (1 - 1/16) · ... · (1 - 1/n%B... |
ke_45 |
Mar-28-09 10:46 AM
by jack202 |
4
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permutations....help please
There are 720 permutations possible from the digits 1 through 6. If you ordered all 720 permutations from smallest to largest, what would the 317th... |
SammiTE |
Dec-14-08 05:35 PM
by Dale Kozniuk |
3
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Bearing problem
Hi,
Our math teacher doesn't explain everything to us, and today he wasn't here and on the homework there's one problem that I have no ide... |
Liliya |
Nov-27-08 11:32 AM
by moo |
3
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