2009 AMC 10B Problem 13
Problem 13 of 25IntermediateGeometryNumber Theory
As shown below, convex pentagon has sides and The pentagon is originally positioned in the plane with vertex at the origin and vertex on the positive -axis. The pentagon is then rolled clockwise to the right along the -axis. Which side will touch the point on the -axis?
Answer choices
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Solution
The pentagon has perimeter One full roll advances the contact point by and
After rolls, vertex sits at and at Rolling further, touches at and at
Since lies between and side touches that point.
Thus, the correct answer is C.