Spherical Triangle: Construction and Angle Measurement on a Sphere

① This example constructs a spherical triangle on a sphere using three great-circle arcs, visually demonstrating the differences between spherical and planar geometry. ② Core mathematical concepts include spherical triangles, spherical angles, great circles, orthogonal planes, and the property that the sum of interior angles of a spherical triangle exceeds 180°. ③ Construction details: The Sphere command creates the sphere, PointIn places points A, B, C on the surface, CircleArc draws the great-circle arcs, Segment connects vertices, Plane and OrthogonalPlane build auxiliary planes, IntersectPath finds intersection curves, and Angle measures the spherical angles, resulting in a labeled triangle. ④ Suitable for high school or university geometry courses, useful for comparing Euclidean and spherical geometry, and as an introductory example in 3D geometric modeling.