11 Nov
2013
11 Nov
'13
8:59 a.m.
Take a circle & look at it along its axis; it appears as a circle. Now tilt the axis of the circle at an angle alpha; it now appears as an ellipse. Consider the foci of the ellipse. Is there anything interesting and/or cool about the relationship of the foci and the angle alpha? (I don't know any interesting answer; I'm just curious.)