Pascal discovered this amazing geometry result when he was only 16. The book "The Art of the Infinite" by Robert Kaplan and Ellen Kaplan has a wonderful introduction to projective geometry and a proof this this theorem.

Proof of Pascal's Theorem for the Circle (which also proves any conic section under projective geometry)
http://mathgardenblog.blogspot.....com/2013/08/hexagra

Proof of Pappus Theorem
http://mathgardenblog.blogspot.....com/2013/08/hexagra

Algebraic proof
http://www.ias.ac.in/mathsci/v....ol120/nov2010/pm-10-

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My Books
"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 3.8/5 stars on 31 reviews)
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"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 5/5 stars on 2 reviews)
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"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.4/5 stars on 13 reviews.
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"Math Puzzles Volume 2" is a sequel book with more great problems. (rated 5/5 stars on 3 reviews)
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"Math Puzzles Volume 3" is the third in the series. (rated 3.8/5 stars on 4 reviews)
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"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews)
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"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 4 reviews)
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"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 3 reviews)
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