See section 12.4.3 for single points of intersection of objects in space.
The single_inter (or the line_inter) command takes two geometric objects as arguments and returns one of the points of intersection of the two objects.
The single_inter command optionally takes a third argument, which can be a point or a list of points. If the optional argument is a single point, then single_inter returns the point of intersection closest to the optional argument. If the optional argument is a list of points, then single_inter tries to return a point of intersection not in the list.
For example, the unit circle circle(0,1) and line
line(-1,i) intersect at the points
(−1,0) and (0,1). Entering
draws the point (−1,0). To draw the other
and Xcas will draw (0,1). Similarly, since this second
point of intersection is closest to (0,1/2), entering
also draws the second point.