The feet of the perpendiculars from any point N on the circumcircle of a triangle T to the sides of the triangle are collinear. The line of collinearity is called the Simson line of the point N for the triangle T

For a detailed description of the Simson line sl, use the routine detail (i.e., detail(sl))

Note that the routine only works if the vertices of triangle T are known.

The command with(geometry,SimsonLine) allows the use of the abbreviated form of this command.

assume that the names of the horizontal and vertical axes are _x and _y, respectively