y_{0} = 1.1 (slider from -5 to 5)
x_{0} = 0.9 (slider from -5 to 5)
f(x, y) = (x^(1) * y^(2))
f_{x} = Derivative(f(x, y), x)
f_{y} = Derivative(f(x, y), y)
z_{0}: f(x_{0}, y_{0})
P: (x_{0}, y_{0}, z_{0})
Kx = CurveCartesian(x_{0} + t, y_{0}, 0, t, -2, 2)
Ky = CurveCartesian(x_{0}, y_{0} + t, 0, t, -2, 2)
Kx3 = CurveCartesian(x_{0} + t, y_{0}, f(x_{0} + t, y_{0}), t, -2, 2)
Kurvey3 = CurveCartesian(x_{0}, y_{0} + t, f(x_{0}, y_{0} + t), t, -2, 2)
a: f_{x}(x_{0}, y_{0})
b: f_{y}(x_{0}, y_{0})
V11 = Vector(P, P + (1, 0, 0))
V2 = Vector(P, P + (0, 1, b))
V1 = Vector(P, P + (1, 0, a))
V21 = Vector(P, P + (0, 1, 0))
α = Angle(V2, V21)
T(x, y) = z_{0} + (f_{x}(x_{0}, y_{0}) * (x - x_{0})) + (f_{y}(x_{0}, y_{0}) * (y - y_{0}))