Constructing Lines of Length sqrt(n) Using Proof by Induction

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Homework Help Overview

The discussion revolves around constructing lines of length sqrt(n) using a given unit length line, with a focus on proof by induction. Participants explore geometric interpretations and the relationships between constructed lengths.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss initial attempts to construct lines of length sqrt(n) using right triangles and the Pythagorean theorem. Questions arise about formalizing these constructions into a proof by induction and generalizing the process for all natural numbers.

Discussion Status

The discussion is active, with participants sharing ideas on how to use previously constructed lengths to derive new ones. There is an exploration of the inductive step, particularly how to transition from sqrt(n) to sqrt(n+1), but no consensus on a formal proof structure has been reached yet.

Contextual Notes

Participants are navigating the constraints of using induction and the requirement to construct lengths based on previously established lines. The problem context emphasizes the need for clarity in definitions and assumptions regarding the construction process.

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Proof by Induction--Sqrt(n)

Homework Statement


Prove that if a line of unit length is given, then a line of length sqrt(n) can be constructed for each n.


Homework Equations


N/A


The Attempt at a Solution



So I'm not really sure where to begin...I assumed that a unit length is the representation of the natural numbers (1, 2, 3...n). And then I drew a triangle with unit length 1 on the legs and then constructed the hypotenuse to be sqrt(2). And then I drew a triangle with unit length 1 on a leg and unit length 2 on a leg and then I constructed the hypotenuse to be sqrt(5). But I don't know how to:

i) Write this as a formal proof by induction, or
ii) How to find some sqrt(n) with unit lengths, like sqrt(3) or sqrt(4).
 
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What if you use the sqrt(2) line that you just constructed to make the sqrt(3) line somehow?
 


Office_Shredder said:
What if you use the sqrt(2) line that you just constructed to make the sqrt(3) line somehow?

So then (sqrt(2))^2+1^2 = c^2
c=sqrt(3)

Ok, that makes sense. Is there a way to generalize this as a rule or equation to prove with induction?

So far I have:

(1^2)+(1^2)=c^2
(1+1) = c^2
c=sqrt(2)

(sqrt(2))^2+1^2 = c^2
2+1 = c^2
c=sqrt(3)

(sqrt(2))^2+(sqrt(2))^2=c^2
2+2 = c^2
c = 2

etc etc?

How would I prove that I can find sqrt(n) for all n, such that n is a natural number?
 


Well, it says to use induction. We can use the line with length sqrt(1) to make a line of length sqrt(2). We can use the line with length sqrt(2) to make a line with length sqrt(3). Given a line of length sqrt(n), can you make a line with length sqrt(n+1)? And how does that help you with a proof by induction?
 

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