Mock AIME 1 2005-2006/Problem 1

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Problem 1

$2006$ points are evenly spaced on a circle. Given one point, find the maximum number of points that are less than one radius distance away from that point.

Solution

Number the points $p_1$, $p_2$, \dots, $p_2006$. Assume the center is $O$ and the given point is p_1. Then $\anglep_nOp_n+1$ (Error compiling LaTeX. Unknown error_msg) = $\frac {\pi}{1003}$, and we need to find the maximum n such that $\anglep_1Op_n+1 \le 60$ (Error compiling LaTeX. Unknown error_msg) degrees ($n+1$ is given so that there are $n$ repetitions of \frac {pi}{1003}). This can be done in $\frac {\frac {\pi}{3}}{\frac {\pi}{1003}$ (Error compiling LaTeX. Unknown error_msg) = $\frac {1003}{3} =$334.333\dots$, so$n$+$1$=$335$. We can choose$p_2, p_3, \dots, p_335$, so$334$points. But we need to multiply by$2$to count the number of points on the other side of$p_1$, so the answer is \boxed{668}.