Hard
Math and Logic
Sphere or Torus using rocks?
Choose an answer
A.Throw a rock and see if it hits
B.Measure the shadow
C.Taste the surface
D.Perpendicular loops
Answer: Perpendicular loops
On a sphere, any two 'great circles' must intersect. On a torus, you can have a loop that goes around the center and another through the hole that never meet.