Some years ago one of our Pure Mathematicians decided to find out if he could make an ellipse by squashing a circle...
If you want to make an ellipse, the easiest way is to do it on a computer because most art or drawing programmes can do ellipses perfectly.
However if you want to do it the old fashioned way, you need to bang two nails into a piece of wood then put a loose loop of string around them. Put a pencil in the string, and keeping the loop tight, draw around. This makes an ellipse for you, and the good bit is that the nails are the foci.
That's all very well, but suppose you've already got an ellipse and want to find the foci? Before you do that, first you need to find the centre and then the axes!
If you want to make an ellipse, the easiest way is to do it on a computer because most art or drawing programmes can do ellipses perfectly.
