This small plastic mode consists of three quadrants of a disc with a common center glued together at right angles to form a spherical triangle with three right angles. Such spherical triangles are ...

That’s Maths: Spherical geometry is central to the study of geophysics and astronomy ... The three angles of a plane Euclidean triangle add to two right angles or 180 degrees.

This cut and glued plastic model shows a spherical triangle formed from three quadrantal (but not perpendicular) sectors of discs. It is unmarked and undated. Location Currently not on view Credit ...