Tractrix (General formula-cartesian coordinates)

Description

Tractrix is the curve along which an object moves, under the influence of friction, when pulled on a horizontal plane by a line segment attached to a tractor (pulling) point that moves at a right angle to the initial line between the object and the puller at an infinitesimal speed. It is therefore a curve of pursuit.
When the branches of the tractrix are meeting at the cusp point (a, 0) then the coordinates’ equation-related to the length of the pulling thread- gives a specific form of curve.