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2009 AMC 10A Problem 19

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2009 AMC 10A Problem 19AMC 10 Step by Step

Name: Date: September 13, 2026

Divisibility & Factors · difficulty 3 of 5 · about 3 min · position P16-20

Circle $A$ has radius $100$ . Circle $B$ has an integer radius $r<100$ and remains internally tangent to circle $A$ as it rolls once around the circumference of circle $A$ . The two circles have the same points of tangency at the beginning and end of circle $B$ 's trip. How many possible values can $r$ have?

A)
$4$
B)
$8$
C)
$9$
D)
$50$
E)
$90$

2009 AMC 10A Problem 19

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