Chebyshev's linkage
Author: Chris Sangwin
Date: 22 Dec 2006

This is Chebyshev's linkage.  Move the point C with the mouse and observe the movement of the point P.  Note that in this linkage the lengths have the following proportions.  AB=CD=5  AD=4 and CB=2, with P at its centre.

A = Point(xAxis)
a = 5
c = Circle(A, a)
D = Point(xAxis)
b = 5
d = Circle(D, b)
C = Point(d)
e = Segment(C, D)
f = 2
g = Circle(C, f)
B = Intersect(c, g, 2)
h = Segment(A, B)
i = Segment(B, C)
P = Midpoint(B, C)
loc1 = Locus(P, C)