I have discovered a truly marvelous proof of this, which
however the margin is not large enough to contain. -- Pierre de Fermat,
referring to the result known as Fermat's Last Theorem
Why is important that someone on this planet understands the geometry
of a triangle?
Well, you use it all the time but often don't notice it and when
you develop a deeper understanding of triangles a tremendous wealth
of information opens to you.