Difference between revisions of "2024 SSMO Accuracy Round Problems/Problem 2"

(Created page with "==Problem== Equilateral triangle <math>N</math> is inscribed within circle <math>O</math>. A smaller equilateral triangle <math>P</math> is inscribed within <math>N</math> su...")
 
 
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==Solution==
 
==Solution==
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WLOG, let the radius of <math>O</math> be 1. Then, the side length of <math>N</math> is <math>\sqrt{3},</math> meaning the side length of <math>P</math> is <math>\frac{\sqrt{3}}{2}.</math> Thus, the answer is <cmath>\frac{\pi}{\left(\frac{\sqrt{3}}{2}\right)^2\cdot\left(\frac{\sqrt{3}}{4}\right)} = \frac{\pi}{\frac{3\sqrt{3}}{16}} = \frac{16\sqrt{3}\pi}{9}\implies 16+3+9 = \boxed{28}.</cmath>
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~SMO_Team

Latest revision as of 14:31, 10 September 2025

Problem

Equilateral triangle $N$ is inscribed within circle $O$. A smaller equilateral triangle $P$ is inscribed within $N$ such that the vertices of $P$ lie on the midpoints of $N$. The ratio of the areas between $O$ and $P$ can be expressed as $\frac{a\pi\sqrt{b}}{c},$ for relatively prime positive integers $a,c$ and squarefree $b.$ Find $a+b+c$.

Solution

WLOG, let the radius of $O$ be 1. Then, the side length of $N$ is $\sqrt{3},$ meaning the side length of $P$ is $\frac{\sqrt{3}}{2}.$ Thus, the answer is \[\frac{\pi}{\left(\frac{\sqrt{3}}{2}\right)^2\cdot\left(\frac{\sqrt{3}}{4}\right)} = \frac{\pi}{\frac{3\sqrt{3}}{16}} = \frac{16\sqrt{3}\pi}{9}\implies 16+3+9 = \boxed{28}.\]

~SMO_Team