Class 9 · Chapter 5
Introduction to Euclid's Geometry
Euclid's definitions, axioms and postulates; the difference between an axiom and a theorem.
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Detailed theory
Around 300 BC, the Greek mathematician Euclid organised the geometry known at the time into a systematic treatise, 'The Elements'. He started with a small list of self-evident truths (axioms and postulates) and derived hundreds of results (theorems) from them.
Key concepts & formulas
01
Axiom (postulate): a self-evident truth assumed without proof.
02
Theorem: statement proved from axioms.
03
Euclid's Postulate 1: a straight line can be drawn from any point to any other.
04
Postulate 3: a circle can be drawn with any centre and radius.
05
Axiom: 'Things equal to the same thing are equal to one another.'
06
The whole is greater than the part.