We start with a given circle.

Geometry construction with compass and straightedge or ruler or ruler
1.  Place the right-angle corner of any object at any point on the circle. Any point will do. Geometry construction with compass and straightedge or ruler or ruler
2.  Make a mark where the two sides of the right-angle cross the circle. Geometry construction with compass and straightedge or ruler or ruler
3.  Draw a line between these two marks. Because of Thales Theorem, this is a diameter of the circle. Geometry construction with compass and straightedge or ruler or ruler
4.  Place the right-angle corner of the object at any other point on the circle. Any point will do, but for greatest accuracy, make it about a quarter the way round the circle from the first point. Geometry construction with compass and straightedge or ruler or ruler
5.  Make a mark where the two sides of the right-angle cross the circle. Geometry construction with compass and straightedge or ruler or ruler
6.  Connect these two points with a straight line. This is the second diameter. Geometry construction with compass and straightedge or ruler or ruler
7.  Done. The point where the two diameters intersect is the center of the circle. Geometry construction with compass and straightedge or ruler or ruler

Why it works

Geometry construction with compass and straightedge or ruler or rulerThis method works as a result of Thales Theorem. The diameter of a circle subtends a right angle to any point on the circle. The converse is also true: A right angle on the circle must cut off a diameter. By finding two diameters, we find the center where they intersect

Visit Thales Theorem for an animated description of how this works.

Views: 293

Replies to This Discussion

This just solved a problem I was anticipating I would run into later. Now I know how to avoid it.

RSS

The Essential Pages

New to Cigar Box Nation? How to Play Cigar Box GuitarsFree Plans & How to Build Cigar Box GuitarsCigar Box Guitar Building BasicsCigar Box Guitar Parts Store

Site Sponsor

Recommended Links & Resources


Discussion Forum

Piezo feedback problems

Started by David Fultz. Last reply by Bernie Edwards Aug 27, 2016. 14 Replies

Bowed instruments

Started by Fomhorach. Last reply by JL Mar 23, 2016. 1 Reply

Ceramic piezo disc as a mic for a reverb spring

Started by Jon Leslie/Runaway Veal Music. Last reply by Fomhorach Mar 1, 2016. 6 Replies

Distortion

Started by Kevin M. Kraft. Last reply by Fomhorach Feb 29, 2016. 16 Replies

Stomp box

Started by smojo. Last reply by JL Jan 4, 2016. 14 Replies

DIY Tremolo

Started by Better Trees. Last reply by Better Trees Mar 10, 2014. 4 Replies

wiring mystery

Started by bucky. Last reply by Bernie Mango Feb 28, 2014. 5 Replies

Fever dream pickup

Started by Bear Peterson Jan 23, 2014. 0 Replies

Ted's Headstock Designs

Started by Ted Crocker. Last reply by Ted Crocker Sep 1, 2013. 2 Replies

Fretting Tips, Tricks & Supplies

Started by Ted Crocker. Last reply by Silent Jim Dec 21, 2011. 1 Reply

How to Find the Center of a Dowel or Circle

Started by Ted Crocker. Last reply by Ryan Rose Nov 6, 2011. 1 Reply

Nut & Bridge Slotting

Started by Ted Crocker. Last reply by Mark Werner Oct 18, 2011. 1 Reply

Printable Harbor Freight Tools Discount Coupons

Started by Ted Crocker. Last reply by Bear Oct 17, 2011. 1 Reply

Ted's Wiring Diagrams & Schematics

Started by Ted Crocker Oct 17, 2011. 0 Replies

Identifying Exotic Woods

Started by Ted Crocker Oct 17, 2011. 0 Replies

not cbg sorry

Started by jon beel. Last reply by ian dawson Sep 28, 2011. 3 Replies

circuit sniffing

Started by petey twofinger. Last reply by Chuck Dubman Jan 5, 2011. 3 Replies

2 prong outlet guitar chord?

Started by Jerryrig240. Last reply by Chuck Dubman Jan 2, 2011. 6 Replies

beer bottle caps

Started by smojo. Last reply by Nick Jan 4, 2010. 8 Replies

Latest Activity

AGP # liked Rich's photo
1 hour ago
AGP # commented on James O Lunsford's video
Thumbnail

Rainy Day Blues

"Appropriate Song also for me in the Land Down Under James O, just had a week of rain down here,…"
2 hours ago
AGP # liked James O Lunsford's video
2 hours ago
AGP # commented on AGP #'s photo
Thumbnail

AGP #466 - ''Theo''

""Thanks Ron", the solid body gits are well worth having a go at, have done quite a few…"
5 hours ago
AGP # commented on AGP #'s photo
Thumbnail

AGP #466 - ''Theo''

""Thanks A.D.", No 78 Records were harmed in the construction of this build, purchased…"
5 hours ago
Rob Uker commented on A.D.EKER's photo
Thumbnail

High Tech Head

"That’s crazy."
5 hours ago
AGP # commented on AGP #'s photo
Thumbnail

AGP #466 - ''Theo''

""Thanks Doug", have used my Pyromaniac Expertise on a few builds over the years. ;-D"
6 hours ago
RON NORTHCUTT commented on AGP #'s photo
Thumbnail

AGP #466 - ''Theo''

"That is a very nice build, I have never done a solid body. May have to give it a go."
6 hours ago
Rob Uker posted a photo
7 hours ago
Rob Uker posted a photo
7 hours ago
Rob Uker posted a photo
7 hours ago
Rich posted photos
11 hours ago

Music

© 2022   Created by Ben "C. B. Gitty" Baker.   Powered by

Badges  |  Report an Issue  |  Terms of Service

\uastyle>\ud/** Scrollup **/\ud.scrollup {\ud background: url("https://storage.ning.com/topology/rest/1.0/file/get/963882636?profile=original") no-repeat scroll 0 0 transparent;\ud bottom: 25px;\ud display: inline !important;\ud height: 40px;\ud opacity: 0.3 !important;\ud position: fixed;\ud right: 30px;\ud text-indent: -9999px;\ud width: 40px;\ud z-index: 999;\ud}\ud.scrollup:hover {\ud opacity:0.99!important;\ud}\ud \uascript type="text/javascript">\ud x$(document).ready(function(){\ud x$(window).scroll(function(){\ud if (x$(this).scrollTop() > 100) {\ud x$('.scrollup').fadeIn();\ud } else {\ud x$('.scrollup').fadeOut();\ud }\ud });\ud x$('.scrollup').click(function(){\ud x$("html, body").animate({ scrollTop: 0 }, 600);\ud return false;\ud });\ud });\ud \ua!-- End Scroll Up -->