This is a historical flowchart proof
about the Nagel Point theorem.
It shows the logical chains of propositions and how the proof of:

Nagel Point theorem depends on
the theorems: Ceva, and Semiperimeter & Excircles.

Ceva's theorem depends on the
Menelaus theorem.

Menelaus theorem depends on
Similarity of triangles and a transversal, etc.
For more details: click on the buttons
Nagel Point, Ceva's theorem, Menelaus theorem, or Semiperimeter
& Excircles.
