2017 AIME I Problems/Problem 8
Problem 8
Two real numbers and are chosen independently and uniformly at random from the interval . Let and be two points on the plane with . Let and be on the same side of line such that the degree measures of and are and respectively, and and are both right angles. The probability that is equal to , where and are relatively prime positive integers. Find .
Solution
Noting that and are right angles, we realize that we can draw a semicircle with diameter and points and on the semicircle. Since the radius of the semicircle is , if , then must be less than or equal to .
This simplifies the problem greatly. Since the degree measure of an angle on a circle is simply half the degree measure of its subtended arc, the problem is simply asking:
Given such that , what is the probability that ?
Through simple geometric probability, we get that .
The answer is
~IYN~
See Also
2017 AIME I (Problems • Answer Key • Resources) | ||
Preceded by Problem 7 |
Followed by Problem 9 | |
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