Fermat’s Problem for Torricelli
Find the point the sum of whose distances from the vertices of a given triangle is
a mininum.
This famous problem was proposed by the French mathematician Fermat (1601-1665)
to the Italian physicist Torricelli (1608-1647), the famous student of Galileo. Torricelli solved
it in several ways.
The answer is
Theorem
1. If all angles in ABC are less than 120, the point O that minimizes the sum
of its distances from vertices A,B,C is the that point inside dABC at which
AOB BOC COA 120
2. If some angle of ABC is 120 or more, say the angle at C, then O = C