To start the applet right click the slider below and activate the animation. 

t = -3 (slider from -5 to 5, step 0.01)
a: RandomUniform[0, 16] + (0 * t)
b: RandomUniform[0, 6.283185307179586] + (0 * t)
B = (5, 3)
C = (10, 3)
D = (5, 6)
E = (10, 6)
c = Segment(B, C)
d = Segment(C, E)
e = Segment(E, D)
f = Segment(D, B)
A: ((sqrt(a) * cos(b)), (sqrt(a) * sin(b)))
F = (0, 0)
g = Circle(F, 4)