Let 
be a curve and let 
be a fixed point. Let 
be on 
and let 
be the curvature center
at 
. Let 
be the point with 
a line segment parallel and
of equal length to 
.
Then the curve traced by 
is the radial curve of 
.
It was studied by Robert Tucker in 1864. The parametric
equations of a curve 
with radial point 
and parameterized by a variable 
are given by
 |  |  |
(1)
|
 |  |  |
(2)
|
Here, derivatives are taken with respect to the parameter 
.
