Spherical Diangle Construction and Measurement

This example demonstrates the construction of a spherical diangle (also called a lune) on a sphere, formed by two great-circle arcs, and shows the relationships among its vertices, edges, and angles. The core mathematical concepts include spherical geometry, great circles, spherical angles, and degenerate spherical triangles. Construction highlights: using GeoGebra commands such as Sphere to create the sphere, PointIn to place points on the surface, Plane and IntersectPath to generate great-circle intersections, Line and OrthogonalPlane for auxiliary lines and perpendicular planes, Angle to measure spherical angles, Intersect to find intersection points, and Segment to draw arcs between points on the sphere. Suitable for high school or university students learning spherical geometry, solid geometry, and spatial vectors, and for exploring differences between spherical and planar angles.