How do you find what the function of a sine wave graph is

Scott92

Scott92

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Hi all so i have a sine wave graph see below, i know red line is sin(x) and i think blue is -cos(5x) but not sure on what green is how can i work it out other than plugging in numbers aimlessly into a graph simulator thanks 1707561153868.png
 
Scott92 said:
Hi all so i have a sine wave graph see below, i know red line is sin(x) and i think blue is -cos(5x) but not sure on what green is how can i work it out other than plugging in numbers aimlessly into a graph simulator thanks View attachment 37109
Click to expand...
Did you make the graphs, or was it just given to you as is? In the former case, what did you enter to make it? In the latter case, where did it come from, and do you have anything other than the image?

It does look very much like the green is sin(x) - cos(5x):
1707573470442.png
 
Scott92 said:
Hi all so i have a sine wave graph see below, i know red line is sin(x) and i think blue is -cos(5x) but not sure on what green is how can i work it out other than plugging in numbers aimlessly into a graph simulator thanks View attachment 37109
Click to expand...
This short (2min) video I've put together may be of interest...
(Click on the picture below then, when the website opens, click the Fullscreen icon and just hit Play to start the video. )

Vimeo site.png​

It may not be exactly what you had hoped for but it certainly seems to support the conclusions suggested above.

Hope that helps. 😊
 
Last edited:
Dr.Peterson said:
Did you make the graphs, or was it just given to you as is? In the former case, what did you enter to make it? In the latter case, where did it come from, and do you have anything other than the image?

It does look very much like the green is sin(x) - cos(5x):
View attachment 37110
Click to expand...
Its a question i have to find a equation that defines the wave form i had put what you said and was told its wrong which confused me as the pictures not great and it looks the same
 
The Highlander said:
This short (2min) video I've put together may be of interest...
(Click on the picture below then, when the website opens, click the Fullscreen icon and just hit Play to start the video. )


It may not be exactly what you had hoped for but it certainly seems to support the conclusions suggested above.

Hope that helps
Click to expand...
Thats pretty epic mate thanks, although I've been told this answer is wrong so im a bit baffled
 
Scott92 said:
Thats pretty epic mate thanks, although I've been told this answer is wrong so im a bit baffled
Click to expand...
Who told you it was wrong?
Or, rather, (perhaps) where were you told it was wrong?
Is this an online quiz of some sort?
Do you enter your answer online and get an immediate response?
If so, is it possible you could direct us to the website in question so that we may see everything there in its entirety and in the correct context?
 
Also, please tell us exactly what the problem said, and exactly what you entered as you answered, and exactly what was said about it. Working with students, I often find that the "error" is a trivial one.
 
Dr.Peterson said:
Did you make the graphs, or was it just given to you as is? In the former case, what did you enter to make it? In the latter case, where did it come from, and do you have anything other than the image?

It does look very much like the green is sin(x) - cos(5x):
View attachment 37110
Click to expand...
All i have is that image and asked to find
The Highlander said:
Who told you it was wrong?
Or, rather, (perhaps) where were you told it was wrong?
Is this an online quiz of some sort?
Do you enter your answer online and get an immediate response?
If so, is it possible you could direct us to the website in question so that we may see everything there in its entirety and in the correct context?
Click to expand...
The waveforms below, show one cycle of a fundamental sinewave (RED), with another sinusoid (BLUE), together with the sum of the two waveforms (GREEN). Give an equation which mathematically defines the GREEN waveform.
1707659127673.png This was my answer its for a HNC question but im missing how im wrong
 
Dr.Peterson said:
Also, please tell us exactly what the problem said, and exactly what you entered as you answered, and exactly what was said about it. Working with students, I often find that the "error" is a trivial one.
Click to expand...
The waveforms below, show one cycle of a fundamental sinewave (RED), with another sinusoid (BLUE), together with the sum of the two waveforms (GREEN). Give an equation which mathematically defines the GREEN waveform.
My answer was 1707659402441.png is it due to fact it could also be -cos(x)+sin(x) maybe
 
Scott92 said:
The waveforms below, show one cycle of a fundamental sinewave (RED), with another sinusoid (BLUE), together with the sum of the two waveforms (GREEN). Give an equation which mathematically defines the GREEN waveform.
My answer was View attachment 37115 is it due to fact it could also be -cos(x)+sin(x) maybe
Click to expand...

So it was graded by a human, whom you could ask for an explanation? You should do that.

I can imagine trivial issues, such as that what you wrote is not an equation, or that they may have wanted the variable to be t rather than x; but it's clear that what you said is generally correct. They told you it's a sum, and your expressions for the red and blue are right, and they don't ask for "the" equation in a particular form; so I don't see any other room for error.
 
Dr.Peterson said:
So it was graded by a human, whom you could ask for an explanation? You should do that.

I can imagine trivial issues, such as that what you wrote is not an equation, or that they may have wanted the variable to be t rather than x; but it's clear that what you said is generally correct. They told you it's a sum, and your expressions for the red and blue are right, and they don't ask for "the" equation in a particular form; so I don't see any other room for error.
Click to expand...
Yeah i probably will ask just wasn't sure if was something glaring obvious that I was missing thanks for the help appreciate it
 
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