Limaçon as a Pedal of a Circle

Given is a circle , and a fixed point . This will be the pedal point.  Let be a random point on , and line be the tangent to the circle at point  . The light blue point is the intersecting point of and the perpendicular through to . As moves along , the foot of the perpendicular (the light blue point) will draw the pedal curve of the circle. This curve will be a Limaçon.
  • Drag point along the circle or press the play button.
  • Move the position of : outside the circle, on the circle, or inside the circle, and see the change in the Limaçon.