HP Prime Graphing Wireless Calculator - Manual (Page 52)

48 Geometry
computed automatically and are saved into the CAS variables
p and q.
Curve
Circle
Draws a circle, given the endpoints of the diameter, or a
center and radius, or an equation in x and y.
circle(point1, point2) or circle(point1, point 2-point1) or
circle(equation)
Examples:
circle(GA, GB) draws the circle with diameter AB.
circle(GA, GB-GA) draws the circle with center at point
A and radius AB.
circle(x^2+y^2=1) draws the unit circle.
This command can also be used to draw an arc.
circle(GA, GB, 0, π/2) draws a quarter-circle with
diameter AB.
Circumcircle
Draws the circumcircle of a triangle; that is, the circle
circumscribed about a triangle.
circumcircle(point1, point2, point3)
Example:
circumcircle(GA, GB, GC) draws the circle
circumscribed about ΔABC
Excircle
Given three points that define a triangle, draws the excircle of
the triangle that is tangent to the side defined by the last two
points and also tangent to the extensions of the two sides
where the common vertex is the first point.
Example:
excircle(GA, GB, GC) draws the circle tangent to
segment BC and to the rays AB and AC.