Chords of CirclesDate: 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/ |
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