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1971 Canadian MO Problems/Problem 1

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Problem

DEB is a chord of a circle such that DE=3 and EB=5 . Let O be the center of the circle. Join OE and extend OE to cut the circle at C. Given EC=1, find the radius of the circle

Image:CanadianMO_1971-1.jpg

Solution

First, extend CO to meet the circle at P. Let the radius be r. Applying power of a point, (EP)(CE)=(BE)(ED) and 2r-1=15. Hence, r=8.

1971 Canadian MO (Problems)
Preceded by
First question
1 2 3 4 5 6 7 8 9 10 Followed by
Problem 2
Looking for a challenging algebra text? Preparing for MATHCOUNTS or the AMC exams?
Check out Art of Problem Solving's Introduction to Algebra by Richard Rusczyk.
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