In the 2-d geometry screen in point mode, clicking on a point with the left mouse button will choose that point. Points chosen this are automatically named, first with A, then B, etc.
Alternatively, the point command chooses a point, where the
point (a,b) is specified by either the two coordinates a,b, a
list [a,b] of the coordinates, or the affix a + b*i.
Input:
or:
or
Input:
Output:
(The marker used to indicate the point can be changed; see section 11.3.2.)
If the point command has two numbers for arguments, at least
one of which is complex but not real, then it will choose two points.
Entering
Input:
or:
will choose two points named A; one with affix 1 and one with affix 2i.