General triangle rules and formulas?

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Discussion Overview

The discussion revolves around basic triangle rules and formulas, particularly focusing on right triangles and Pythagorean triples. Participants explore various mathematical properties and patterns related to triangles, including specific integer combinations that form valid triangles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks resources for reviewing basic triangle rules and formulas, particularly for right triangles.
  • Another participant presents a formula for generating Pythagorean triples using integers a and b: X=a²-b², Y=2ab, Z=a²+b², asserting that X² + Y² = Z².
  • A link to a resource on Pythagorean triples is shared, suggesting it may provide useful information.
  • Another contribution discusses a method for generating triples from any odd integer n, providing examples for n=3, 5, and 7.
  • Concerns are raised about the case when n=1, questioning the validity of a triangle with a zero-length side.
  • Participants discuss the concept of degeneracy in triangles, with one suggesting that the triangle collapses to a line segment when n=1.
  • There is a light-hearted mention of negative numbers, indicating a playful tone amidst the confusion.

Areas of Agreement / Disagreement

Participants express confusion regarding the implications of certain integer values on triangle validity, particularly at n=1. There is no consensus on how to interpret this case, with some suggesting it leads to a degenerate triangle while others remain uncertain.

Contextual Notes

Some participants reference mathematical concepts and properties without fully resolving the implications or definitions, particularly regarding degeneracy and the conditions under which certain formulas apply.

Euphoriet
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Hi guys I'm looking for a website where I can review basic triangle rules such as the formulas for right triangles... I would look at a geometry book but I don't have one. Its been a long time and I need some reviewing to do.

I also wanted to ask if anyone knew about the group of triangles such as one with sides measuring 4,5,3... , 24,25, 7 etc? This are the typical SAT triangles.. and I know there is a patter but I don't know what it is.

Thanks.
 
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Given integers, a and b, the entire pattern is generated by

[tex]X=a^2-b^2, Y=2ab, Z=a^2+b^2, where X^2 +Y^2 = Z^2.[/tex]

You can check this by multiplication and by reading Modern Algebra by Birkhoff and MacLane.
 
Last edited:
Also, given any odd interger 'n', [tex]\frac {n^2 + 1}{2}, ~\frac {n^2 - 1}{2}[/tex] complete a triple.

Thus, for 3, you have 4=(9-1)/2 and 5 =(9+1)/2
for 5, you have 12 = (25-1)/2, 13 = (25+1)/2
then there's 7, 24, 25 and 9, 40, 41 and so on..
 
Gokul43201 said:
Also, given any odd interger 'n'...

but what's going on at n = 1?
a zero length side on a triangle can't be possible. :confused:


or maybe we're not talking strictly about triangles?
 
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So what statement is true?.. I'm lost now
 
Math Is Hard said:
but what's going on at n = 1?
a zero length side on a triangle can't be possible. :confused:


or maybe we're not talking strictly about triangles?

You've got a "degenarate" case here:
Two "sides" of length 1, one "side" with length 0; that is a straight line segment of length 1 traversed in opposite directions when going around your "triangle" (ending up on your starting point)
 
this is getting confusing now =-/
 
I think our triangle just collapses to line segment when n = 1, that's all.
But correct me if I am wrong, arildno.
 
  • #10
That's what I meant, Math is hard ("degeneracy" is a word often used in similar cases).
 
  • #11
Negative numbers anyone?

hehe
 

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