Euclid The Elements • Taught in Alexandria, Egypt. – 13 books in all.

325-265 BC
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• Author of The Elements
– 13 books in all.
– Standard textbook for Geometry for about
2000 years.
• Taught in Alexandria, Egypt.
Euclid’s Elements:
The first 4 axioms
A modern form of the axioms.
1. For every point P and every point Q not equal to P there
exists a unique line that passes through P and Q.
2. For every segment AB and for every segment CD there
exists a unique point E such that B is between A and E
and the segment CD is congruent to segment BE.
3. For every point O and every point A not equal to O there
exists a circle with center O and radius OA.
4. All right angles are congruent to each other.
Euclid’s Elements:
The Parallel Postulate
That, if a straight line falling on two straight lines make
the interior angle 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.