Is there a specific notation to denote which angle is the orthogonal angle of a right triangle?

Question

If an exercise says "the right triangle $ABC$" is there an order of the letters to signify which angle is the orthogonal angle? For example

$ABC$ is a right triangle means $\hat B=90$ degrees

$BAC$ is a right triangle means $\hat A=90$ degrees

etc.

Answer 1

In text, one convention is to use $\quad\angle ABC=\angle\theta=\pi=90^\circ.\quad$ In the case of $\angle ABC$ the letter in the middle is generally the vertex containing the angle. (Think of $x=AB, y=BC, z=AC).\quad$ In drawing, it is common to put a small square inside the "figure" as shown in the crude image below.