The radial curve of the deltoid

			(1)
			(2)

with pedal point is

			(3)
			(4)

With the pedal point at a cusp, this is the folium

			(5)
			(6)

For the pedal point opposite the cusp (i.e., at the negative -intercept), it is the bifolium

			(7)
			(8)

At the center, it is the trifolium

			(9)
			(10)

In fact, the pedal curve is a trifolium for any pedal point on the inscribed equilateral triangle.

CITE THIS AS:

Weisstein, Eric W. "Deltoid Pedal Curve." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/DeltoidPedalCurve.html