2003 AMC 12B Problems/Problem 21
Problem
An object moves cm in a straight line from to , turns at an angle , measured in radians and chosen at random from the interval , and moves cm in a straight line to . What is the probability that ?
Solution 1 (Trigonometry)
By the Law of Cosines,
It follows that , and the probability is .
Solution 2
, let the object turn clockwise.
Note that the possible points of create a semi-circle of radius and center . The area where is enclosed by a circle of radius center .
Let . Function of , function of .
is the point that satisfies both functions.
, , , ,
Note that is a triangle, as , , . As a result , .
Therefore the probability that is
See also
2003 AMC 12B (Problems • Answer Key • Resources) | |
Preceded by Problem 20 |
Followed by Problem 22 |
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All AMC 12 Problems and Solutions |
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