The Euclidean EEAT says that an exterior angle isequalto the sum of the two opposite angles. That is, of course, because the exterior angle is 180 degrees minus the adjacent angle in the triangle and, since the angles in a Euclidean triangle sum to 180 degrees, that is the same as sum of the two opposite angles. On a sphere, the angle in a triangle sum tomorethan 180 degrees so the exterior angle islessthan the sum of the two opposite angles. In hyperbolic geometry, the angles in a triangle sum to [b]less[b] than 180 degrees so the exterior angle isgreaterthan the sum of the two opposite angles.