This is the homepage of Evan Chen (known also as vEnhance on certain websites). I'm an MIT grad student and a math olympiad coach.
My CV is here. Here is a list of my major coursework from undergraduate and graduate school. These days, I'm interested in number theory and combinatorics. My papers are linked on my publications page, and also on the arXiv.
The nine-point circle of $\triangle BIC$ is orthogonal to the circle with diameter $ST$.
Problem source: Taiwan TST Quiz 2015
Evan is a math PhD student at MIT and one of the United States math olympiad coaches. In addition to serving as the team selection coordinator for the United States, Evan runs his own training program while streaming olympiad math for public entertainment.
As a high school student, Evan was an IMO gold medalist and a winner of the 2014 USA math olympiad, which he took from 12:30am to 5am in Taiwan. He also wrote the popular textbook Euclidean Geometry in Math Olympiads while in high school, which was published in 2016.
Outside of math and teaching, Evan's hobbies include Korean pop dance, Arch Linux, Hanabi and puzzle hunts.