Construct an equilateral triangle

From a line section, using a compass and straight edge, it is possible to construct an equilateral triangle.

Starting with a line segment

By putting a compass point on each point that defines the line segment, draw two crossing arcs above the line segment

Drawing a line segment from one of the points on the original line segment through the crossed arches creates an angle of .

Joining up the other point to the crossed arcs finishes the construction of the equilateral triangle.