Determine the domain and range of limit

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Homework Help Overview

The discussion revolves around a problem involving the dynamics of a thin equilateral triangular block rotating about a vertex under the influence of gravity. The original poster seeks to determine the domain and range of a function f(x) that represents the final x-coordinate of a point on the triangle after it has rotated until a side touches the x-axis. The problem also includes questions about discontinuities and fixed points of the function.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between the initial position of the midpoint M and the final position f(x). They raise questions about the behavior of the function for different values of x, including cases where x is positive, negative, or zero. Some participants suggest breaking down the problem into smaller questions to clarify understanding.

Discussion Status

There is an ongoing exploration of the problem, with participants providing guidance in the form of questions aimed at clarifying the original poster's understanding. Multiple interpretations of the function's behavior are being discussed, particularly regarding its domain and range, as well as the conditions under which it may be discontinuous.

Contextual Notes

Participants note confusion regarding the definitions of domain and range in the context of the problem, as well as the implications of the triangle's orientation and position on the final x-coordinate of M.

ussjt
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diagram: http://img.photobucket.com/albums/v629/ussjt/math3.jpg

A thin equilateral triangular block of the side length 1 unit has its face in the vertical xy-plane with vertex V at the origin. Under the influence of gravity, it will rotate about V until a side hits the x-axis floor (see diagram). Let x denote the inital x-coordinate of the midpoint M of the side opposite V, and let f(x) denote the final x-coordinate of the point. Assume that the block balances when M is directly above V.

(a) Determine the domian and range of f
(b) Where on the domain is f discontinuous
(c) Identify any fixed points of f

I have no clue how to go about answering the question. Any help/hints on solving each part would be great, thanks.
 
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ussjt said:
diagram: http://img.photobucket.com/albums/v629/ussjt/math3.jpg

A thin equilateral triangular block of the side length 1 unit has its face in the vertical xy-plane with vertex V at the origin. Under the influence of gravity, it will rotate about V until a side hits the x-axis floor (see diagram). Let x denote the inital x-coordinate of the midpoint M of the side opposite V, and let f(x) denote the final x-coordinate of the point. Assume that the block balances when M is directly above V.

(a) Determine the domian and range of f
(b) Where on the domain is f discontinuous
(c) Identify any fixed points of f

I have no clue how to go about answering the question. Any help/hints on solving each part would be great, thanks.
You labelled the thread limit help, but I see no limit in your problem... :frown: Am I missing something?
First off, do you understand what the problem says? It says you will have different M's initial positions if you place the triangle differently, in other word, you will have different x if you place the triangle differently. And for every position, you will have a final position for M (namely f(x)). So for every x, you have one f(x). Is f(x) a function of x?
-----------
Before tackling the problem, let's answer some questions:
1. So what is x if M is right above V? What's f(x) in that case?
2. If x > 0, then what happen to the triangle? What's f(x) in that case?
3. If x < 0, then what happen to the triangle? What's f(x) in that case?
4. So what's the range of f?
5. What's the maximum value x can have? What's the minimum value?
6. So what's the domain of f?
7. From question 1 to 3, where on the domain is f discontinuous?
8. What's the definition of a fixed point? From here, can you point out the fixed points?
 
VietDao29 said:
You labelled the thread limit help, but I see no limit in your problem... :frown: Am I missing something?
First off, do you understand what the problem says? It says you will have different M's initial positions if you place the triangle differently, in other word, you will have different x if you place the triangle differently. And for every position, you will have a final position for M (namely f(x)). So for every x, you have one f(x). Is f(x) a function of x?
-----------
Before tackling the problem, let's answer some questions:
1. So what is x if M is right above V? What's f(x) in that case?
2. If x > 0, then what happen to the triangle? What's f(x) in that case?
3. If x < 0, then what happen to the triangle? What's f(x) in that case?
4. So what's the range of f?
5. What's the maximum value x can have? What's the minimum value?
6. So what's the domain of f?
7. From question 1 to 3, where on the domain is f discontinuous?
8. What's the definition of a fixed point? From here, can you point out the fixed points?
Sorry about the name, that is what the title was on the page in the book.

I am a little confused still, so for the range, do you mean the highest point m will reach to the lowest(which is 0,1). Also for the domain, I am really confused about that part.
 
ussjt said:
Sorry about the name, that is what the title was on the page in the book.

I am a little confused still, so for the range, do you mean the highest point m will reach to the lowest(which is 0,1). Also for the domain, I am really confused about that part.
Okay, I think you should read the problem again, and then my post. Then can you please try to answer all of them one by one (from 1 to 8), so that I can know what you don't understand.
If M is place slightly to the negative x-axis (i.e x < 0), will the triangle rotate clockwise, or counter-clockwise? When it reaches the x-axis, it stops rotating, what's the x-coordinate of M at that time? What's f(x)?
If M is right above V (it means its initial x-coordinate is 0, x = 0), will it rotate? So what's f(0)?
If M is slightly to the positive x-axis (i.e, x > 0). What's f(x), the final x-coordinate of M?
Do you fully understand what the question asks now? :smile:
 
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