178 Geometry
Example:
incircle(GA, GB, GC) draws the incircle of ΔABC.
locus
Given a first point and a second point that is an element of (a
point on) a geometric object, draws the locus of the first point
as the second point traverses its object.
locus(point,element)
parabola
Draws a parabola, given a focus point and a directrix line, or
the vertex of the parabola and a real number that represents
the focal length.
parabola(point,line) or parabola(vertex,real)
Examples:
parabola(GA, GB) draws a parabola whose focus is point
A and whose directrix is line B.
parabola(GA, 1) draws a parabola whose vertex is point
A and whose focal length is 1.
Transform
dilation
Dilates a geometric object, with respect to a center point, by
a scale factor.
homothety(point, realk, object)
Example:
homothety(GA, 2, GB) creates a dilation centered at
point A that has a scale factor of 2. Each point P on geometric
object B has its image P’ on ray AP such that AP’=2AP.
inversion
Draws the inversion of a point, with respect to another point,
by a scale factor.
inversion(point1, realk, point2)
Example:
inversion(GA, 3, GB) draws point C on line AB such
that AB*AC=3. In this case, point A is the center of the
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