Coxeter- Figure 7.7B

Let [i]A[/i] be a noninvariant point, and [i]l[/i] a noninvariant line through [i]A[/i]. Suppose the given collineation transforms [i]A[/i] into [i]A'[/i], [i]A'[/i] into [i]A''[/i], [i]l[/i] into [i]l'[/i], [i]l'[/i] into [i]l''[/i], [i]l''[/i] into [i]l'''[/i].