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# Geometry Mathematicians: Thales, Eratosthenes, and Euclid.

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## Lauren Reddy

on 14 September 2011

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#### Transcript of Geometry Mathematicians: Thales, Eratosthenes, and Euclid.

Eratosthenes Mathematician, Inventor, Librarian, and Poet 276 BC 194 BC Early Life Born in 275 BC
Born in Cyrene
Current day Libya Education Studied in Athens at Plato's School
Studied under:
Lysanias of Cyrene (Scholar)
Ariston of Chios (Philosopher)
Callimachus of Cyrene (Poet and Scholar) The Sieve of Eratosthenes The Circumfrence of the Earth Geography First person to use the word "Geography"
Created the concept of Longitude and Latitude
Calculated the circumfrenece of Earth, the tilt of Earth's axis, the distance from Earth to the sun
Invented Leap Day How it works: Make a list of numbers 1-100
Mark 1 as special because it is neither prime, nor composite
2 is a prime number, and will equal m.
Mark all the numbers that are equal to 2m, 3m, 4m, etc. as composite.
repeat the steps above, but with the next number. Repeat this step until you have done the number 7. Thales philosopher, scientist, mathematician brought back study of geometry from Egypt to Greece
none of his works survived the time of Aristotle, another mathematician
some think that he predicted the first eclipse of the sun
measured the heights and shadows of pyramids Fun Facts 5 Theorems of Geometry A circle is bisected by any diameter
The base angles of an isoceles triangle are equal
An angle in a semicircle is a right triangle University of Alexandria Became a Librarian after Callimachus died
Tutored Ptolemy III Euergetes son, Philopator Death Became Blind in 194 B.C.
Died of self-inflected starvation
Would rather die, than not be able to read
Died at age 82 Well at Syene had no Shadow on June 21st
Well in Syene, 500 miles from pillar in Alexandria
Measured pillar in Alexandria at 7.5 degrees
Alternate interior angle
7.5 degrees is about 1/50 of a circle
multiply 50 times distance from well to pillar (500 miles)
The circumfrence about 25,000 Name Origin seperates wanted elements from unwanted elements using a mesh screen.
Metaphorically seperating prime numbers from composite Eratosthenes Life Euclid "There is no royal road to geometry" Facts • Called the “Father of Geometry”
• Wrote 10 major works including his most famous “Elements” which was dealing with algebra, geometry, and number theory.
• Famous quote “There is no royal road to geometry.”
• His book, “Elements” has been the only book, except for the Bible to be translated, edited and studied more.
• Was a Modest, friendly man, always kind and patient.
• Know as a model of accuracy, imagination, determination and logical thinking.
• Wasn’t a mathematical genius, but he contributed greatly to math through his expository skills. The 3 Mathematicians Thales, Eratosthenes, and Euclid By Aidan Cadley, Stefanie Kushner, and Lauren Reddy, 330-275 BC
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