We consider the rational linear relations between real numbers whose squared trigonometric functions have rational values, angles we call ``geodetic.'' We construct a convenient basis for the vector space over Q generated by these angles. Geodetic angles and rational linear combinations of geodetic angles appear naturally in Euclidean geometry; for illustration we apply our results to equidecomposability of polyhedra.
['John H. Conway', 'Charles Radin', 'Lorenzo Sadun']
On Angles Whose Squared Trigonometric Functions are Rational