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maths question help

Can anyone helps with this question please? Not sure what topic this is/ where to even start. C2B54AE7-8491-4BA9-B3E2-D2A1F8851668.jpg.jpeg

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Reply 1
Original post by subbhy
Can anyone helps with this question please? Not sure what topic this is/ where to even start.


Do you know what the sine graph looks like?
Reply 2
Original post by Muttley79
Do you know what the sine graph looks like?


yes but not sure what sort of transformation they want me to do
Original post by subbhy
yes but not sure what sort of transformation they want me to do

When sketching graphs, it's often less efficient to think in terms of transformations.
If you know how the sine graph looks like, mark some critical points (i.e. points where you can easily find without much heavy calculations), then "fit" the sine graph onto them.

So... what are some of the critical points? That'd be your job. In fact, the question requires you to do so (i.e. "label the important values on the axes").
Reply 4
Original post by tonyiptony
When sketching graphs, it's often less efficient to think in terms of transformations.
If you know how the sine graph looks like, mark some critical points (i.e. points where you can easily find without much heavy calculations), then "fit" the sine graph onto them.

So... what are some of the critical points? That'd be your job. In fact, the question requires you to do so (i.e. "label the important values on the axes").

I disagree - what evidence do you have to say that?
Reply 5
Original post by subbhy
yes but not sure what sort of transformation they want me to do


So you know what - sine looks like? Then what does the '5' do?
Original post by Muttley79
I disagree - what evidence do you have to say that?

From experience. At least it works for me. (In other words, no evidence)
That said, if others find thinking in transformations to be easier, then good for you. No "best method" here as long as you get the job done when it comes to curve sketching, IMO.

I just find it very confusing in the particular case of, say, transforming y=f(x) to y=f(2x). I'd rather just find the easy points, like the zeros/max/min/intercepts, and fit the graph in.
(edited 8 months ago)
Reply 7
Original post by tonyiptony
From experience. At least it works for me. (In other words, no evidence)
That said, if others find thinking in transformations to be easier, then good for you. No "best method" here as long as you get the job done when it comes to curve sketching, IMO.

I just find it very confusing in the particular case of, say, transforming y=f(x) to y=f(2x). I'd rather just find the easy points, like the zeros/max/min/intercepts, and fit the graph in.

That won't work if they ask for the transformations though ...
Original post by Muttley79
That won't work if they ask for the transformations though ...


Well, sure... But if method is not specified, I don't really care.
Reply 9
Original post by tonyiptony
Well, sure... But if method is not specified, I don't really care.


It's good practice to think transformation or you are risking losing marks if you can't do it that way.
Reply 10
Original post by Muttley79
So you know what - sine looks like? Then what does the '5' do?


No idea
Original post by subbhy
No idea


Really? Have you been taught this topic?

All the y values are 5 times bigger ...
Reply 12
Original post by subbhy
Can anyone helps with this question please? Not sure what topic this is/ where to even start. C2B54AE7-8491-4BA9-B3E2-D2A1F8851668.jpg.jpeg

well, all you really need to know is what the regular sine graph looks like and what each number represents. (Asin(Bx+C)+D)
-5 here represents the amplitude, and to find the top and bottom critical points, you add/subtract the vertical translation from the amplitude.
+7 represents a vertical translation, meaning you move the entire graph up 7 spaces.
here's a hint, the critical value at 90 degrees is y=2.
(edited 8 months ago)
Reply 13
Original post by Muttley79
Really? Have you been taught this topic?

All the y values are 5 times bigger ...


I’ve done simple transformations like translations but not that. Is that stretching?
Reply 14
Original post by stemguy
well, all you really need to know is what the regular sine graph looks like and what each number represents. (Asin(Bx+C)+D)
-5 here represents the amplitude, and to find the top and bottom critical points, you add/subtract the vertical translation from the amplitude.
+7 represents a vertical translation, meaning you move the entire graph up 7 spaces.
here's a hint, the critical value at 90 degrees is y=2.


Thanks for this response.

So essentially for every point I multiply by -5 and add 7?

Normally on the sine graph the point would be (90,1)
1 x -5 = -5
-5 + 7 = 2
So (90,2)

And I do this for all the main points?
Reply 15
Original post by subbhy
Thanks for this response.

So essentially for every point I multiply by -5 and add 7?

Normally on the sine graph the point would be (90,1)
1 x -5 = -5
-5 + 7 = 2
So (90,2)

And I do this for all the main points?


If youve done transformations, you should for a standard sin() graph
* -1 multiplier means reflect in the x axis
* 5 multiplier means stretch by 5 (rescale y axis)
* + 7 means vertical translation by 7
Its not wrong to pick points on a standard sin() and multiply by -5 and add 7, but Id guess the question is more about getting you to understand the basic transformations.
Original post by stemguy
well, all you really need to know is what the regular sine graph looks like and what each number represents. (Asin(Bx+C)+D)
-5 here represents the amplitude, and to find the top and bottom critical points, you add/subtract the vertical translation from the amplitude.
+7 represents a vertical translation, meaning you move the entire graph up 7 spaces.
here's a hint, the critical value at 90 degrees is y=2.

Not really what s needed ...
Reply 17
Original post by subbhy
Thanks for this response.

So essentially for every point I multiply by -5 and add 7?

Normally on the sine graph the point would be (90,1)
1 x -5 = -5
-5 + 7 = 2
So (90,2)

And I do this for all the main points?


Perfect, you got it. Use that trick to quickly find all the points you need(remember, you don’t need more than 2/3 since the values will repeat with a longer period)
Good job!
Reply 18
Original post by Muttley79
Not really what s needed ...

Would you mind clarifying why it isn’t needed, instead of giving a vague reply?
Reply 19
This is true, I’m just letting him know about how you’d calculate those values quickly in the exam.

Original post by mqb2766
If youve done transformations, you should for a standard sin() graph
* -1 multiplier means reflect in the x axis
* 5 multiplier means stretch by 5 (rescale y axis)
* + 7 means vertical translation by 7
Its not wrong to pick points on a standard sin() and multiply by -5 and add 7, but Id guess the question is more about getting you to understand the basic transformations.

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