What is the difference between constructing a square and constructing an equilateral triangle? for the square construction, the diameter will be used, but for the equilateral triangle construction, the radius will be used. for the square construction, the radius will be used, but for the equilateral triangle construction, the diameter will be used. the square construction will need two arcs along the circle, but the equilateral triangle construction will need two arcs above and two arcs below the diameter of the circle. the square construction will need three arcs along the circle, but the equilateral triangle construction will need two arcs above and two arcs below the diameter of the circle.