Measure like an Egyptian │ The History of Mathematics with Luc de Brabandère
How did the ancient Egyptians measure the Earth?
Some 4000 years ago - and without any of our modern equipment.
Find out how applying basic logic to the rays of the Sun gave birth to geometry.
Philosopher Luc de Branbandère guides us through the history of mathematics, from Egyptians measuring with the Sun to modern algorithms for self-driving cars.
Find out more: https://en.wikipedia.org/wiki/Egyptia...
Our ‘History of Maths’ series continues with a look at how Egyptians used the Sun to invent geometry and measure the Earth.
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Mathematics is made up of different areas. The first discipline was definitely arithmetic. We just saw the invention of the digit, the invention of the number and another discipline which came from Egypt. It was called geometry. Geometry comes from geo and metron- how to measure the Earth and that's what they did. Imagine thousands of years ago, Egyptians succeeded in measuring the circumference of the planet. How did they do it?
Egypt is a strange country with a River Nile and the Nile is vertical. And at a given place, the Nile crosses the Tropic of Cancer and those people, the Egyptians realise that once a year at noon, if you sink a post on the Tropic of Cancer, there is no shadow. The Sun is vertical. So, what did they do? They put another post 800 kilometres north and on the same day at the same time, they noticed there is a shadow. So, they measured the angle and they realised the angle was seven degrees, so it's not too difficult then to realise that if you take the angle here starting from the centrum of the planet, it must be seven as well. And now it was easy, if seven equals 800 kilometres, they realised that 360 degrees would equal something like 41,000 kilometres. Can you imagine that? Four thousand years ago, people were able to measure and to evaluate the length forty-one thousand kilometres. It's extraordinary.
Next time we look at how Pythagoras built on the Egyptians work to explore the right-angled triangle.
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