the cone gives us the cone in Figure 6(a). (A better alternative would be to
use a more durable plastic cone and adjust the circular sectors accordingly.)
They should see that the surface of the bisecting sector is flat while those of
the others are curved, indicating that the great-circle path is the shortest one,
comparable to a straight line being the shortest path between two points.
Students should also notice that the arcs of the sectors outline a sphere’s
surface, indicating that these arcs represent paths on the surface. Since the
arc lengths can be directly compared and the bisecting sector has the shortest
arc, the same conclusion can be reached more concretely.