Parabolas are just a special case of ellipses where one focus is infinitely far away. Vi Hart has a nice explanation: https://www.youtube.com/watch?v=v-pyuaThp

Parabolas are just a special case of ellipses where one focus is infinitely far away. Vi Hart has a nice explanation: https://www.youtube.com/watch?v=v-pyuaThp-c https://www.youtube.com/watch?v=v-pyuaThp-c