Khan/khan-exercises — pull request #94446 by petercollingridge (2013-10-22 15:50:05+00:00)
Title: Parabola intuition

Added another intuition exercise, where students drag the focus and directrix to try to match a given equation.
For Trello card: https://trello.com/c/y1WCGdK6/402-modify-existing-exercise-parabola-intuition-2