The right lines I𝜇 and 𝜇M, and the length AI²/4S𝜇, are equal among themselves.
For 4S𝜇 is the latus rectum of the parabola belonging to the vertex 𝜇.
Library · Mathematical Principles of Natural Philosophy · Book III
Lemma IX
Isaac Newton
The right lines I𝜇 and 𝜇M, and the length AI²/4S𝜇, are equal among themselves.
For 4S𝜇 is the latus rectum of the parabola belonging to the vertex 𝜇.