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2011 AMC 10A Problem 25

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2011 AMC 10A Problem 25AMC 10 Step by Step

Name: Date: September 13, 2026

Triangles: Area & Pythagorean · difficulty 5 of 5 · about 12 min · position P21-25

Let $R$ be a square region and $n\ge4$ an integer. A point $X$ in the interior of $R$ is called $n\text{-}ray$ partitional if there are $n$ rays emanating from $X$ that divide $R$ into $n$ triangles of equal area. How many points are 100-ray partitional but not 60-ray partitional?

A)
$1500$
B)
$1560$
C)
$2320$
D)
$2480$
E)
$2500$

2011 AMC 10A Problem 25

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