Given a regular polygon with $n$ sides. It is known that there are $1200$ ways to choose three of the vertices of the polygon such that they form the vertices of a right triangle. What is the value of $n$?
Source: OMK 2018 Sulong, Section A Problem 3
Tags: combinatorics, polygon
Given a regular polygon with $n$ sides. It is known that there are $1200$ ways to choose three of the vertices of the polygon such that they form the vertices of a right triangle. What is the value of $n$?