# 11/23: Group A: Graphs (Prof. Bruce Rothschild);

Group B: Inversion with respect to a circle (Olga Radko)

**Graphs:** We will learn about simple properties of graphs through problem-solving.

** Inversion: ** Inversion with respect to a circle is a spectacular geometric transformation of the plane that allows to solve some seemingly unapproachable problems. E.g., the following two problems posed by an ancient Greek mathematician Appolonius:

Using a compass and a ruler, construct a circle tangent to three given circles;
Given two fixed points on the plane, find the set of all points whose distance to the first fixed point is k times the distance to the other point.