Your vision with and without trigonometry

Abstract

When you take a look at anything close-by, your brain computes the position of the object you see by solving a lanky triangle — namely the one formed with the object and your two eyes as its vertices. The brain may call other clues also into service while figuring out positions, especially when the lanky triangles prove far too lanky to afford trigonometric solutions with reasonable accuracy. These non-trigonometric alternatives can run into occasional pitfalls, though. Yet even the trigonometric highway isn’t always foolproof, either. We shall see in what follows that the resulting consequences can be as instructive as they are amusing.