Leitlinie
y = 3 - √(2.6^2 + 3^2) = 3 - √394/5
Scheitel der Parabel
y = 1/2*(3 - √394/5) = 3/2 - √394/10
Parabel
f(x) = a·x^2 + (3/2 - √394/10)
f(2.6) = a·2.6^2 + (3/2 - √394/10) = 3 --> a = 5·√394/338 + 75/338
f(x) = (5·√394/338 + 75/338)·x^2 + (3/2 - √394/10) ≈ 0.5155·x^2 - 0.4849