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Finding the converse of Euclid's fifth postulate (parallel postulate)

by jdinatale
Tags: converse, euclid, parallel, postulate
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Sep6-11, 10:21 PM
P: 155
1. The problem statement, all variables and given/known data

I have to state the converse of the following sentence:

That, if a straight line falling on two straight lines makes the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than two right angles.

3. The attempt at a solution

The statement is a mouthful, so I just want to make sure I got the converse right.

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Stephen Tashi
Sep7-11, 12:14 AM
Sci Advisor
P: 3,252
I think you'd do better to begin "If two lines produced indefinitely meet on a side of a straight line that falls upon them then on that side ...."

Are you taking old fashioned geometry?
Sep7-11, 06:39 AM
Sci Advisor
PF Gold
P: 39,346
The converse of any statement of the form "if A then B" is "if B then A".

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