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Originally published at https://physicsgarage.com on April 12, 2020.
Ptolemy was an ancient astronomer, geographer, and mathematician who lived from (c. AD 100 — c. 170) by Julia Fisher in Cantor’s Paradise.
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| Ptolemy Source: https://www.wikipedia.org/ |
He is most famous for proposing the model of the “Ptolemaic system”, where the Earth was considered the center of the universe, and the stars revolve around it. This was the generally accepted view for many centuries, until Copernicus (19 February 1473–24 May 1543) proposed the theory where the sun was the center with earth an other planets revolving around it.
Although, Ptolemy’s most famous idea turned out to be wrong, he did a lot of really useful work in geometry and we are going to discuss one of those very nice ideas.
Ptolemy’s Inequality
The statement of Ptolemy’s inequality is
You might have seen a similar version for triangles, which is called the triangle inequality. Let us now see how to prove this...
Inequalities like these are incredibly efficient at solving some really hard problems in mathematics and physics.
Source: Medium
