This is amazing!<p>This video compares and contrasts three different types of Geometries:<p>o Spherical Geometry<p>o Euclidian Geometry (the one we all know)<p>o Hyperbolic Geometry<p>With the wonderful property that<p><i>Spherical Geometry is sort of the opposite of Hyperbolic Geometry</i>...<p>(Note to self, have to do more research on this!), i.e.,<p>Circumference of a circle:<p>Spherical: 2 x pi x sin(r)<p>Euclidian: 2 x pi x r<p>Hyperbolic: 2 x pi x sinh(r)