# Constructing a Parabolic Salt Ridge

- Author:
- Darryl Yong

Salt was poured on top of a piece of cardboard with a straight edge and a circle. The bottom of the image below is the straight edge of the cardboard. Construct the points that make up the parabolic ridge of the salt.
Hint: If P is a point on the parabola, then
distance from P to the line = distance from P to the circle = (distance from P to O) - (radius of the circle)
Therefore,
(distance from P to the line) + (radius of the circle) = distance from P to O
You can download this GeoGebra sketch using this link: http://tube.geogebra.org/material/download/format/file/id/1402897