# Fibonacci = Pythagoras: Help save a beautiful discovery from oblivion | Summary and Q&A

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December 3, 2022
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Mathologer
Fibonacci = Pythagoras: Help save a beautiful discovery from oblivion

## TL;DR

The Fibonacci sequence and Pythagorean triples have a fascinating relationship, as demonstrated by their connection in constructing triangles with integer sides and their overlap in certain families of triples.

## Key Insights

• ❓ The Fibonacci sequence can be used to generate Pythagorean triples and explore their properties.
• 👶 The connections between the Fibonacci sequence and Pythagorean triples are surprising and offer new insights into their mathematical relationship.
• 👪 The Pythagorean triple tree highlights the connections between parent and child triangles and how they inherit certain properties.
• 📏 Euclid's theorem explains how to generate all primitive Pythagorean triples using specific rules for choosing integers.

## Transcript

Welcome to another Mathologer video. In 2007 a  simple beautiful connection between two seemingly   unrelated mathematical gems was discovered.  However, it appears that this discovery   has largely gone unnoticed and is actually in  danger of being forgotten. So, I thought let’s   do something about this sorry state of affairs and  Mathologerise t... Read More

### Q: What are the two mathematical gems mentioned in the video?

The two mathematical gems are the iconic identity of 3 squared plus 4 squared equals 5 squared and the super famous Fibonacci sequence.

### Q: How are the Fibonacci sequence and Pythagorean triples connected?

The Fibonacci sequence can be used to generate Pythagorean triples by picking pairs of numbers and calculating their products. These products reveal connections to Pythagorean triangles and their properties.

### Q: How many ways are there to pick two numbers from the Fibonacci sequence in the red box?

There are six ways to pick two numbers from the Fibonacci sequence in the red box, each providing information about the 3-4-5 triangle's properties, such as the incircle and excircle radiuses.

### Q: Are there isosceles triangles with integer sides?

No, right-angled isosceles triangles with integer sides do not exist, as the square root of 2 is an irrational number and cannot be expressed as a fraction with integer sides.

## Summary & Key Takeaways

• The iconic identity of 3 squared plus 4 squared equals 5 squared represents the connection between Pythagorean triples, which are right-angled triangles with integer side lengths, and the Fibonacci sequence.

• By bending the Fibonacci sequence and picking pairs of numbers to calculate their products, surprising connections to the 3-4-5 triangle and other Pythagorean triples are revealed.

• The Fibonacci sequence can be used to generate a Pythagorean triple tree, where each parent triangle's excircles and incircle correspond to the children triangles' excircles and incircle, respectively.