2003 AMC 12B Problems/Problem 10
Contents
[hide]Problem
Several figures can be made by attaching two equilateral triangles to the regular pentagon ABCDE in two of the five positions shown. How many non-congruent figures can be constructed in this way?
Solution
Place the first triangle. Now, we can place the second triangle either adjacent to the first, or with one side between them, for a total of
Solution 2
Take to realize there are 10 ways to choose 2 different triangles. Then divide by 5 for each vertex of a pentagon to get
See Also
2003 AMC 12B (Problems • Answer Key • Resources) | |
Preceded by Problem 9 |
Followed by Problem 11 |
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All AMC 12 Problems and Solutions |
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