In: Math
Prove the Converse of Proposition 3.3 by using Betweenness Axiom 1. The converse is Given B ? C ? D and A ? B ? D, then A ? B ? C and A ? C ? D. Please do not use "by mapping of letters"
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Given: and
To prove: and
Proof: (Method 1)
Now Betweenness Axiom 1: If , then A,B, and C are three distinct points all lying on the same line, and
According to the converse of proposition 3.3 If , then B, C and D are three distinct points.
We can infer from this that Pt C lies between B and D .....................................(1)
If , then A, B and D are three distinct points and Pt B lies between Pts A and D.
Now, as Pt C lies between B and D and Pt B lies between A and D. So it means that points B and C lies between A and D.
From statement 1, we could infer that it is Pt B which lie between A and C.
......................(2)
Now can also be ...............(3)
From 2 and 3, we can infer
Thus implies Pts A, B, C and D are four distinct points.
Method 2:
If then .......................(1) (Betweenness property)
and then ...................(2)
From1 and 2 ,
It means that Pts A, B , C and D are four distinct points such that
Thus proved