Questions tagged [pythagorean-triples]

Questions about Pythagorean triples, positive integer solutions to $a^2 + b^2 = c^2$.

Pythagoras' Theorem states that in any right angle triangle, the length of the hypotenuse squared is equal to the sum of the squares of the lengths of the two shorter sides. If we denote the side lengths of a right angle triangle by $a$, $b$, and $c$, where $c$ is the length of the hypotenuse, then we can restate Pythagoras' Theorem as $a^2 + b^2 = c^2$.

A Pythagorean triple is a triple of positive integers $(a, b, c)$ such that $a^2 + b^2 = c^2$. For any such triple, there is a right angle triangle with side lengths $a$, $b$, and $c$. A Pythagorean triple is called primitive if $\gcd(a,b,c)=1$. There are infinitely many primitive Pythagorean triples: $(3,4,5)$, $(5,12,13)$, $(8,15,17)$, and so on.

614 questions
155
votes
1 answer

Pythagorean triples that "survive" Euler's totient function

Suppose you have three positive integers $a, b, c$ that form a Pythagorean triple: \begin{equation} a^2 + b^2 = c^2. \tag{1}\label{1} \end{equation} Additionally, suppose that when you apply Euler's totient function to each term, the equation…
54
votes
6 answers

Prove that the sum of pythagorean triples is always even

Problem: Given $a^2 + b^2 = c^2$ show $a + b + c$ is always even My Attempt, Case by case analysis: Case 1: a is odd, b is odd. From the first equation, $odd^2 + odd^2 = c^2$ $odd + odd = c^2 \implies c^2 = even$ Squaring a number does not change…
spyr03
  • 1,004
  • 7
  • 22
35
votes
2 answers

Is $100$ the only square number of the form $a^b+b^a$?

Conjecture: $100$ is the only square number of the form $a^b+b^a$ for integers $b>a>1$. In other words, $(a,b)=(2,6)$ is the only solution. Can we prove/disprove this? Observations: The solution mentioned should not come as a surprise, since…
30
votes
2 answers

How does Wiles' proof fail at $n=2$?

The content is miles outside what I know about. So the question is a mixture of idle curiosity and maybe having this answered somewhere on the Internet. It is likely I will not be able to understand the answer. How exactly does Wiles' proof of…
30
votes
5 answers

How do you find Pythagorean triples that approximately correspond to a right triangle with a given angle?

Given an angle $\theta$, can I find a Pythagorean triple $(A,B,C)$ such that the corresponding right triangle contains an angle that is as close to $\theta$ as I want? And if so, how? For example suppose $\theta = 56.25^\circ$. How do I find…
Mike Pierce
  • 18,262
  • 12
  • 63
  • 117
22
votes
1 answer

Four squares such that the difference of any two is a square?

I. This post asks to find $4$ integers $a,b,c,d$ such that the difference between any two is a square. As mentioned by my answer, it is equivalent to finding $3$ squares such that the difference of any two is also a square. With the positive answer…
22
votes
4 answers

Pythagorean triplets of the form $a^2+(a+1)^2=c^2$ and the space between them

I was searching for pythagorean triples where $b=a+1$, and I found using a python program I made the first 10 integer…
22
votes
5 answers

Can two perfect squares average to a third perfect square?

My question is does there exist a triple of integers, $a
Elliot
  • 807
  • 6
  • 12
21
votes
6 answers

A very different property of primitive Pythagorean triplets: Can number be in more than two of them?

While playing with numbers, I thought about squares of numbers, and then the first thing that came to mind was Pythagorean triplets. I observed a very interesting fact that any $x\in\mathbb N$ can never be a member of more than two Pythagorean…
20
votes
5 answers

Is it possible to get arbitrarily near any acute angle with Pythagorean triangles?

The scatter graph at the Wikipedia article seems to suggest so. Has anyone attacked this before? Is there a known proof?
JCCyC
  • 649
  • 4
  • 11
20
votes
2 answers

$x^2+y^2=z^n$: Find solutions without Pythagoras!

I was presented with the following problem: Prove that there exist solutions to $x^2+y^2=z^n$ for all $n$, with $x,y,z, n \in \mathbb{N}$ I showed that by taking any Pythagorean triple $x^2+y^2=z^2$ and multiplying by $z^{2(n-1)}$ we get…
acernine
  • 1,738
  • 13
  • 18
18
votes
6 answers

Does any given integer only occur in one primitive Pythagorean triple?

I know that all integers are part of at least one primitive triple. But can this statement be refined to exactly one? From looking at some lists of triples it seems to be true, but I have no clue where I'd start in showing it. Update: I'm not sure…
clb
  • 313
  • 2
  • 8
16
votes
7 answers
16
votes
6 answers

Near-Pythagorean triplets: What are the general solutions to $a^2+b^2=c^2-1$?

Obtaining the most general solution to a quadratic Diophantine equation in three variables is often easier if the equation is homogeneous. For example, by focusing on "primitive" solutions, it is easy to show that all Pythagorean triplets can be…
Mark Fischler
  • 40,850
  • 2
  • 36
  • 70
15
votes
0 answers

when $F_n^2+F_m^2$ is a square for fibonacci numbers

This is a curiosity question I'm trying to solve a Diophantine equation and I need some results about fibonnacci numbers, I encountered this problem: For which couple of integers $(n,m)$ the number $F_n^2+F_m^2$ is a square where $F_k$ denotes the…
1
2 3
40 41