It is said that he discovered the proposition relating to the exterior angle of a triangle.
The sharp edge formed by two surfaces meeting at an exterior angle.
The proposition relating to the exterior angle was recognized by Pappus of Alexandria.
If one side of a triangle be produced, the exterior angle shall be greater than either of the interior opposite angles.
Posterior wings white, with a sooty spot on each near the external edge, and a very faint small mark near the exterior angle.
The angle formed between a side of a polygon and an extended adjacent side. Compare interior angle.