the first image showing a "Spherical triangle needs a minor correction. Only two of the interior angles are labeled, (Alpha and Beta) The third has a simple circle as a label. If the intent is to show a general spherical triangle, it should be labeled gamma to indicate is variable. If the intent is to show a Right Spherical Triangle, it should be labeled as such, and a right angle corner symbol should label the third angle. It appears to my eye that the image protrays a "right" triangle.