Three Properties of Isogonal Conjugates

In this post I'll cover three properties of isogonal conjugates which were only recently made known to me. These properties are generalization of some well-known lemmas, such as the incenter/excenter lemma and the nine-point circle. 1. Definitions Let $latex {ABC}&fg=000000$ be a triangle with incenter $latex {I}&fg=000000$, and let $latex {P}&fg=000000$ be any point in… Continue reading Three Properties of Isogonal Conjugates

Set Theory, Part 2: Constructing the Ordinals

This is a continuation of my earlier set theory post. In this post, I'll describe the next three axioms of ZF and construct the ordinal numbers. 1. The Previous Axioms As review, here are the natural descriptions of the five axioms we covered in the previous post. Axiom 1 (Extensionality) Two sets are equal if… Continue reading Set Theory, Part 2: Constructing the Ordinals

Set Theory, Part 1: An Intro to ZFC

Back in high school, I sometimes wondered what all the big deal about ZFC and the Axiom of Choice was, but I never really understood what I read in the corresponding Wikipedia page. In this post, I'll try to explain what axiomatic set theory is trying to do in a way accessible to those with… Continue reading Set Theory, Part 1: An Intro to ZFC