f(x, y) = (x^(0.5) * y^(0.5))
a = 0.4 (slider from -5 to 5)
b = 1.2 (slider from -5 to 5)
g = Ray((0, 0), (a, b))
c = CurveCartesian((a * t), (b * t), f((a * t), (b * t)), t, 0, 10)
h = 5 (slider from -5 to 5, step 1)
d(x, y) = h
e = ImplicitCurve(f(x, y) - h)
A, A_1 = Intersect(e, g)
i(x, y) = f(x, y)
f1 = Derivative(f(x, y), x)
f2 = Derivative(f(x, y), y)
a1: f1(A)
b1: f2(A)
k(x) = ((-(a1 / b1)) * x) + y(A) + (a1 / b1 * x(A))