See section 11.15.5 for homotheties in the plane.
The homothety command takes two or three arguments. The first argument is a point, the center of the homothety. The second argument is a real number, which is the scaling ratio. The optional third argument is the object which is transformed.
With two arguments, homothery returns a new command which
performs the dilation.
returns and draws the point (0,0,2), which is the point (0,0,1) dilated by a factor of 2 away from (0,0,0).
With a third argument of a geometric object, homothety
returns and draws the dilated object.
returns and draws (0,0,2), as above.
returns and draws the sphere of radius 2 centered at (0,0,0).