On Friday, October 11, 2013 11:10:28 PM UTC+2, RichD wrote: > One can construct an ellipse as follows: > > pin 2 thumbtacks into a sheet, loop a string > > (tied at the ends) loosely around them, pull > > it taut, draw the ellipse with a pencil; the > > sum of the distances etc. > > > > Are there similar methods to draw a parabola > > and hyperbola? >