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counting and probability intermediate
Problem
Real numbers and are chosen independently and uniformly at random from the interval . Which of the following numbers is closest to the probability that and are the side lengths of an obtuse triangle?
(A)
(B)
(C)
(D)
Solution
The Pythagorean Inequality tells us that in an obtuse triangle, . The triangle inequality tells us that . So, we have two inequalities: The first equation is of a circle with radius , and the second equation is a line from to . So, the area is which is approximately
Final answer
C