one way to label the right-angled triangle
In many German textbooks, the following labelling of the right-angled triangle is used when working on Pythagoras’ Theorem. Vertices (Eckpunkte) are labelled A, B and C (anti-clockwise). The opposite sides (gegenüberliegenden Seiten) to the vertices are labelled a,b and c, respectively. And the angles are labelled with Greek letters alpha, beta and gamma: $${\alpha, \space \beta \space\text{and}\space \gamma}$$ The hypotenuse c = q + p. The altitude (height) hc is the height perpendicular to the side c (hypotenuse) passing through C.