HP Prime Graphing Calculator - Manual (Page 189)

Geometry 185
parameq
Works like the equation command, but returns parametric
results in complex form.
parameq(GeoObj )
perimeter
Returns the perimeter of a polygon or the circumference of a
circle.
perimeter(polygon)
or
perimeter(circle)
Examples:
If GA is the point at (0, 0), GB is the point at (1, 0), and GC
is defined as circle(GA, GB-GA), then perimeter(GC)
returns 2.
If GA is the point at (0, 0), GB is the point at (1, 0), and GC
is defined as square(GA, GB-GA), then perimeter(GC)
returns 4.
radius
Returns the radius of a circle.
radius(circle)
Example:
If GA is the point at (0, 0), GB is the point at (1, 0), and GC
is defined as circle(GA, GB-GA), then radius(GC) returns 1.
Test
is_collinear
Takes a set of points as argument and tests whether or not they
are collinear. Returns 1 if the points are collinear and 0
otherwise.
is_collinear(point1, point2, …, pointn)
Example:
is_collinear(point(0,0), point(5,0),
point(6,1)) returns 0