Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Chords of Circles


Date: 02/28/2001 at 21:59:59
From: Robert
Subject: Chords of Circles

There is a circle with radius 10 and a chord XY 8cm long. How far is 
the chord from O, the center of the circle? 

I cannot figure out how to do it. My book has congruent chords and the 
distance to one chord, so it's in the picture and all you do is 
substitute. I do not know how to start.


Date: 02/28/2001 at 22:52:13
From: Doctor Peterson
Subject: Re: Chords of Circles

Hi, Robert.

Draw the circle and chord AB. (I'll wait while you get a pencil ...)

Okay, now draw lines from the center O of the circle to the ends of 
the chord, A and B.

Finally, draw a line from the center of the circle to the midpoint of 
the chord, C.



Now let's look at the picture. Can you see that OC is the 
perpendicular bisector of AB? That gives you a right triangle OCA. You 
know the lengths of OA and AC; Pythagoras can help you find OC.

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Conic Sections/Circles
Middle School Geometry

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/