HP Prime Graphing Wireless Calculator - Manual (Page 61)

Geometry 57
if GA is the point at (0, 0) and GB is defined as
plotfunc(4–x^2/4), then distance (GA, GB) returns 3.464…
or 2√3.
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.
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 2π.
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.
Slope
Returns the slope of a straight object (segment, ray, or line).
slope(Object)
Example:
slope(line(point(1, 1), point(2, 2))) returns 1.
Area
Returns the area of a circle or polygon.
area(circle) or area(polygon)
This command can also return the area under a curve
between two points.
area(expr, value1, value2)