How To Prove This Theorem In Projective Geometry

HOW TO PROVE THIS THEOREM IN PROJECTIVE GEOMETRY: GIVEN FOUR DISTINCT POINTS A,B,C,D ON A LINE, THERE EXIST PROJECTIVITIES WHICH CARRY A)A,B,C,D INTO B,A,D,C B) A,B,C,D INTO D,C,B,A C) A,B,C,D INTO C,D,A,B RESPECTIVELY.

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