Ellipse & Hyperbola Construction by Circle
A nice way to construct an ellipse or hyperbola, inspired by the PCMI summer 15, problem set 7, questions 14 and 18.
http://mathforum.org/pcmi/hstp/sum2015/morning/darryl/day07.pdf
Thanks to Tina Cardone, Bowen Kerins and Darryl Yong.