1983 AIME Problems/Problem 12
Revision as of 18:52, 15 February 2019 by Sevenoptimus (talk | contribs) (Fixed the problem statement and diagram)
Problem
Diameter of a circle has length a -digit integer (base ten). Reversing the digits gives the length of the perpendicular chord . The distance from their intersection point to the center is a positive rational number. Determine the length of .
Solution
Let and . It follows that and . Applying the Pythagorean Theorem on and , .
Because is a positive rational number, the quantity cannot contain any square roots. Either or must be 11. However, cannot be 11, because both must be digits. Therefore, must equal eleven and must be a perfect square (since ). The only pair that satisfies this condition is , so our answer is .
See Also
1983 AIME (Problems • Answer Key • Resources) | ||
Preceded by Problem 11 |
Followed by Problem 13 | |
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