GCSE Maths trigonometric graph question help please?

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londoncricket
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Hi all,

Please look at the attachment. It is question 26(c) from the Edexcel GCSE Mathematics A Paper 1 (Non-Calculator) 1MA0/1H Monday 9 June 2014 paper

The solutions are:

"a = 2
b = 2
c = 1"

I understand how to arrive at the answer for "a = 2" and "c = 1", but how do I calculate "b = 2"?

Please help.

Thank you!
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M.C. Math
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(Original post by londoncricket)
Hi all,

Please look at the attachment. It is question 26(c) from the Edexcel GCSE Mathematics A Paper 1 (Non-Calculator) 1MA0/1H Monday 9 June 2014 paper

The solutions are:

"a = 2
b = 2
c = 1"

I understand how to arrive at the answer for "a = 2" and "c = 1", but how do I calculate "b = 2"?

Please help.

Thank you!
Hi.

That question wouldn't be out of place on the Edexcel C2 paper for AS students!!

Incidentally, b is not 2. cos bx is a horizontal stretch of the cos x graph, scale factor 1/b, so see how many complete waveforms you can observe over a 360 degree period (one normal cycle for the cos x graph), and that will be the value of b.
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londoncricket
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(Original post by M.C. Math)
Hi.

That question wouldn't be out of place on the Edexcel C2 paper for AS students!!

Incidentally, b is not 2. cos bx is a horizontal stretch of the cos x graph, scale factor 1/b, so see how many complete waveforms you can observe over a 360 degree period (one normal cycle for the cos x graph), and that will be the value of b.
Thanks for your reply!

Ah really? Must be the A* level content of GCSE Maths then.

Sorry about that, I meant 3, not 2, for the solution to "b".

Oh I see, so does that work for the sine graph too?

Thank you very much for your help!
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M.C. Math
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(Original post by londoncricket)
Thanks for your reply!

Ah really? Must be the A* level content of GCSE Maths then.

Sorry about that, I meant 3, not 2, for the solution to "b".

Oh I see, so does that work for the sine graph too?

Thank you very much for your help!
You're welcome!

Yes, it would be true for the sine graph too.

In general, for any function of x, f(x), then f(3x) is a horizontal stretch of 1/3.
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londoncricket
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(Original post by M.C. Math)
You're welcome!

Yes, it would be true for the sine graph too.

In general, for any function of x, f(x), then f(3x) is a horizontal stretch of 1/3.
Great, thanks for all of that!
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