Reflective Property of the Parabola
Author: cwl

Drag the point A on the parabola y=x² and observe
the slope of the tangent line.  How does this slope
relate to the coordinates of A?

Drag the point A to see the reflective property of
the parabola.

A = Point(c)
a = Tangent(A, c)
b = Slope(a)
B = (0, 0.25)
d = OrthogonalLine(A, xAxis)
C = Point(d)
e = Ray(A, C)
f = Segment(A, B)
D = Point(a)
α = Angle(D, A, C)
E = Point(a)
β = Angle(B, A, E)
g = Line(A, B)