The identification of this point was posed as a challenge by

Pierre de Fermat to

Evangelista Torricelli. For this reason, the point is usually known as the

Fermat point or the

Fermat-Torricelli point.

The usual construction of this point is, given the triangle ABC, to construct a point D, on the opposite side of BC to A, such that BCD is equilateral. The Fermat/Fermat-Torricelli/Steiner point is the intersection of AD with the circumcircle of BCD.