Difference between revisions of "2001 AMC 10 Problems/Problem 5"
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== Problem == | == Problem == | ||
| − | How many of the twelve pentominoes at least one line of symmetry? | + | How many of the twelve pentominoes pictured below at least one line of symmetry? |
<math> \textbf{(A)}\ 3 \qquad \textbf{(B)}\ 4 \qquad \textbf{(C)}\ 5 \qquad \textbf{(D)}\ 6 \qquad \textbf{(E)}\ 7 </math> | <math> \textbf{(A)}\ 3 \qquad \textbf{(B)}\ 4 \qquad \textbf{(C)}\ 5 \qquad \textbf{(D)}\ 6 \qquad \textbf{(E)}\ 7 </math> | ||
| + | |||
| + | == Solution == | ||
| + | |||
| + | Here is the picture: http://www.artofproblemsolving.com/Forum/download/file.php?id=6659&&mode=view | ||
| + | |||
| + | The ones with lines over the shapes have at least one line of symmetry. Counting the number of shapes that have line(s) on them, | ||
| + | we find $ \boxed{\textbf{(D)} 6} pentominoes. | ||
== Solution == | == Solution == | ||
Revision as of 13:27, 16 March 2011
Problem
How many of the twelve pentominoes pictured below at least one line of symmetry?
Solution
Here is the picture: http://www.artofproblemsolving.com/Forum/download/file.php?id=6659&&mode=view
The ones with lines over the shapes have at least one line of symmetry. Counting the number of shapes that have line(s) on them, we find $ \boxed{\textbf{(D)} 6} pentominoes.
