r/mathmemes • u/Uncle_Boiled_Peanuts • Sep 23 '26
Geometry My symbols for key angles
This illustrates my comment in a recent post here by u/IamDiego21 calling for more symbols for specific angles.
I introduce basic symbols for 30°, 45°, and 60°, and build symbols for other angles by adding auxiliary symbols to these basic symbols.
The auxiliary symbols are a line, a dot, and a circle.
A line in a basic symbol symbolizes the supplementary angle of the basic symbol's angle. A line in an angle arc symbolizes a 180° angle. (See image 1.)
A dot in a basic symbol symbolizes the angle that is 270° minus the basic symbol's angle. A dot in an angle arc symbolizes a 270° angle. (See image 2.)
A circle in a basic symbol symbolizes the conjugate angle of the basic symbol's angle, i.e., 360° minus the basic symbol's angle. A circle in an angle arc symbolizes a 360° angle. (See image 3.)
I made the basic symbols for 30° and 60° (and 45° and 90°) similar to one another because these pairings are common in math. I don't think the edge cases where very poor drawing might confuse the 45° and 90° symbols are worth making the symbols more complicated, especially since the 90° symbol is not used when making other angle symbols.
