TI 84 plus not showing graph correctly,help?

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Discussion Overview

The discussion revolves around an issue with graphing a mathematical function using a TI-84 Plus calculator. Participants explore the reasons for discrepancies between the expected graph and the output from the calculator, focusing on the function h(t) = 20 + (1/2π)cos(2πt) + t*sin(2πt) and its parameters.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant reports that their TI-84 Plus is not displaying the graph correctly and provides the function and parameters used.
  • Another participant suggests that the issue was resolved by manually calculating 1/(2π) as approximately 0.16, indicating a potential misunderstanding related to radians.
  • A third participant questions the original equation, noting a possible typo and mentions that their graphing program agrees with the calculator's output, suggesting that the sinusoidal behavior may require zooming out to be visible.
  • This participant also points out a potential misunderstanding regarding the notation used for multiplication, questioning whether "Xsin(...)" was intended as a function or a multiplication operation.
  • Two participants confirm that typing the function as 20 + 1/(2π)cos(2πX) + X*sin(2πX) produces the desired graph on their calculators.

Areas of Agreement / Disagreement

There is no consensus on the correct form of the function or the expected graph. Some participants agree on the output of their calculators, while others question the original equation and its interpretation.

Contextual Notes

Participants express uncertainty regarding the notation and the implications of using radians versus decimal approximations. There are unresolved questions about the correctness of the original function and its representation.

Swizaw
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Hello,my Ti 84 plus calculator from texas is showing incorrectly the graph,i can't find out why it's showing incorrectly.

The function is h(t)= 20+(1/2pi)cos(2pit)+tsen(2pit)

t is a variable representing the time
xmin is 0
xmax is 1.
ymin is 19.
ymax is 21
You have to intersect it after with 19,5.This exercise was on my maths 2016 exam (1st phase) and it's not showing the same graph as the resolution.
I attached the picture of what it should look like the correct one
And the one that shows on my calculator
https://imgur.com/M7eyuuP
 

Attachments

  • Screen Shot 2016-07-12 at 19.41.03.png
    Screen Shot 2016-07-12 at 19.41.03.png
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Found what what's wrong,i had to manually do 1/2pi which was like 0.16 and instead of putting 1/2pi i had to put 0.16,probably because it's in radian it was messing up something,you can lock the thread!
Thanks
 
Swizaw said:
Hello,my Ti 84 plus calculator from texas is showing incorrectly the graph,i can't find out why it's showing incorrectly.

The function is h(t)= 20+(1/2pi)cos(2pit)+tsen(2pit)

t is a variable representing the time
xmin is 0
xmax is 1.
ymin is 19.
ymax is 21
You have to intersect it after with 19,5.This exercise was on my maths 2016 exam (1st phase) and it's not showing the same graph as the resolution.
I attached the picture of what it should look like the correct one
And the one that shows on my calculator
https://imgur.com/M7eyuuP
Is there a typo in your original equation? I used a graphing program (see below) and I'm agreeing with your calculator. (In order to see the sinusoidal behavior that my graph displays you need to zoom out.) The vertical lines are 0.1 apart.

-Dan

View attachment 5709

Addendum: You wrote "Xsin(...)" on your calculator. Mine would call that the function Xsin() as opposed to X * sin(). Is this an error or does yours understand the intention?

- - - Updated - - -

topsquark said:
Is there a typo in your original equation? I used a graphing program (see below) and I'm agreeing with your calculator. (In order to see the sinusoidal behavior that my graph displays you need to zoom out.) The vertical lines are 0.1 apart.

-Dan
Addendum: You wrote "Xsin(...)" on your calculator. Mine would call that the function Xsin() as opposed to X * sin(). Is this an error or does yours understand the intention?

PS I just read your response above and I still don't agree with the supposed correct answer. The first "hump" in the graph doesn't exist and the correct graph has a zero around x = 0.31.
 

Attachments

  • Graph.jpg
    Graph.jpg
    27.4 KB · Views: 148
Typing $20+1/(2\pi)\cos(2\pi X)+X\sin(2\pi X)$ gives the desired graph (on my TI-84 Plus).
 
Last edited:
greg1313 said:
Typing $20+1/(2\pi)\cos(2\pi X)+X\sin(2\pi X)$ gives the desired graph (on my TI-84 Plus).
Oh! 0.16. I see it now.

-Dan
 

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