Tangent approximation to sqrt(x)
Author: Don Bindner
Date: 7 February 2014

f(x) = sqrt(x)
A = (4, 2)
a = Tangent(A, f)
B = Point(xAxis)
b = Line(B, yAxis)
C = Intersect(f, b, (1.5, 1.224744871391589))
c = Line(C, xAxis)
D = Intersect(a, b)
d = Line(D, xAxis)