2006 AMC 12B Problems/Problem 23
Contents
Problem
Isosceles has a right angle at . Point is inside , such that , , and . Legs and have length $s=\sqrt{a+b\sqrt{2}{$ (Error compiling LaTeX. Unknown error_msg), where and are positive integers. What is ?
Solution
Using the Law of Cosines on , we have:
Using the Law of Cosines on , we have:
Now we use .
Note that we know that we want the solution with since we know that . Thus, .
Solution 2
Rotate triangle 90 degrees counterclockwise about so that the image of rests on . Now let the image of be . Note that , meaning triangle is right isosceles, and . Then . Now because and , we observe that , by the Pythagorean Theorem on . Now we have that . So we take the cosine of the second equality, using that fact that , to get . Finally, we use the fact that and use the Law of Cosines on triangle to arrive at the value of .
See also
2006 AMC 12B (Problems • Answer Key • Resources) | |
Preceded by Problem 22 |
Followed by Problem 24 |
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All AMC 12 Problems and Solutions |