Trompe L'oeil, maybe, though it's not really related to the Math, Algebra, Geometry category.
trompe l'oeil
It is how 2 is defined so it is not an illusion.
Because the person who created the unit defined a revolution as 360 degrees.
Visual texture
What is the difference between predefined function and user defined functions
its not real texture its one of the other two
Perspective, perhaps.
trompe l'oeil
trompe l'oeil
trompe l'oeil
trompe l'oeil
It is how 2 is defined so it is not an illusion.
linear perspective
Visual texture.
linear perspective
Liberty Defined was created in 2011.
Glory Defined was created in 2004.