CTK Exchange
Front Page
Movie shortcuts
Personal info
Awards
Reciprocal links
Terms of use
Privacy Policy

Interactive Activities

Cut The Knot!
MSET99 Talk
Games & Puzzles
Arithmetic/Algebra
Geometry
Probability
Eye Opener
Analog Gadgets
Inventor's Paradox
Did you know?...
Proofs
Math as Language
Things Impossible
My Logo
Math Poll
Other Math sit's
Guest book
News sit's

Recommend this site

Manifesto: what CTK is about Search CTK Buying a book is a commitment to learning Table of content Things you can find on CTK Chronology of updates Email to Cut The Knot Recommend this page

CTK Exchange

Subject: "Circles..."     Previous Topic | Next Topic
Printer-friendly copy     Email this topic to a friend    
Conferences The CTK Exchange Guest book Topic #197
Reading Topic #197
Mister Meneely
guest
Apr-02-02, 10:31 PM (EST)
 
"Circles..."
 
   How do you find the center of a given circle w/ no tools; just a pencil?


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
alexb
Charter Member
1366 posts
Apr-03-02, 07:03 AM (EST)
Click to EMail alexb Click to send private message to alexb Click to view user profileClick to add this user to your buddy list  
1. "RE: Circles..."
In response to message #0
 
   What is the length of the pencil? Is it'sharp enough? Is it the same color as the circle? Was it used to draw the circle in the first place? Are you allowed to use a pen instead? Is a button a tool? Is a zipper attached to trousers a tool?


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
what name?
guest
Apr-11-02, 11:44 AM (EST)
 
2. "RE: Circles..."
In response to message #0
 
   can you fold the paper?? then it becomes really easy ;)


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
bluediamond
Member since Apr-9-02
Apr-12-02, 12:05 PM (EST)
Click to EMail bluediamond Click to send private message to bluediamond Click to view user profileClick to add this user to your buddy list  
3. "RE: Circles..."
In response to message #2
 
   It might, but then you'd have the problem of defining a set of axioms for paper-folding as well :)


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
pilar
guest
Jan-30-04, 09:50 AM (EST)
 
4. "RE: Circles..."
In response to message #0
 
   you pick three points from the circunference, you draw the triangle, and then you find the (circuncentro) of the triangle.
i don't know how it's exactly circuncentro in english.
you may do it with a pencil and a compass, using the pencil itself as a ruler.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
Bob S
Member since Nov-13-04
Nov-15-04, 04:01 PM (EST)
Click to EMail Bob%20S Click to send private message to Bob%20S Click to view user profileClick to add this user to your buddy list  
5. "RE: Circles..."
In response to message #0
 
   Place the pencil in the approximate center and rotate the circle; move the pencil until it, (the pencil) stops wobbling then you have found the center. Hints, the faster you rotate the circle the easier it is to observe the wobble, also use a sharp pencil. Luck, Bob.
thebobguy


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top

Conferences | Forums | Topics | Previous Topic | Next Topic

You may be curious to visit the old Guest book.
Please do not post there.

|Front page| |Contents| |Store|

Copyright © 1996-2018 Alexander Bogomolny

[an error occurred while processing this directive]
Search:
Keywords:

Google
Web CTK

Latest on CTK Exchange
error found
Posted by kathleen styer
1 messages
04:40 PM, Mar-11-09

geometric proof
Posted by Lawrence
2 messages
06:56 PM, May-05-09

Construction in Geometry
Posted by nicoleg
0 messages
00:50 AM, May-21-09

The square root of 2 is irrational
Posted by Monty
6 messages
06:44 PM, May-21-09

An odd generalisation of prime ro ...
Posted by Derren
0 messages
04:45 PM, Mar-26-09

Trig Inequality
Posted by Bractals
0 messages
06:37 PM, May-21-09