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A level maths. Differentiation of arcsin (x)?

Discussion in 'Mathematics' started by gainly, Jan 31, 2019.

  1. gainly

    gainly Lead commenter

    The Edexcel Year 2 Pure Maths book shows differentiation of arcsin (x) etc. However this is not mentioned in the specification and in the Formula Book it is only given under Further Maths. Does anyone know if it is safe to ignore this for A level maths students?
     
  2. briceanus

    briceanus New commenter

    It shouldn't be in the book, its a mistake. It's only further.
     
    gainly likes this.
  3. gainly

    gainly Lead commenter

    Thank you for clearing that up.
     
  4. briancant

    briancant Occasional commenter

    I would teach it because the use of the chain rule and the trig identities are in the specification. There are no skills that haven't been taught needed to differentiate arcsin, arccos and arctan and for that matter other inverse functions.
     
  5. briancant

    briancant Occasional commenter

    I've just checked the specification. It explicitly mentions differentiating arcsin etc in section 7.4....
     
  6. BG54

    BG54 New commenter

    Yes, it appears that if there is any oversight it's the omission of the first derivatives of the inverse trig functions from the A-level Formula sheets.
     
  7. gainly

    gainly Lead commenter

    Section 7.4 mentions differentiating x = sin(y). I suppose you could take it that implies differentiating y = arcsin(x) but it's not mentioned explicitly.
     
  8. BG54

    BG54 New commenter

    You must have a different edition of the Edexcel spec., in my version (Issue 3, Dec.2017) section 7.4 reads :-

    "Differentiation of cosec x, cot x and sec x and differentiation of arcsin x, arccos x and arctan x are required...."
     
  9. gainly

    gainly Lead commenter

    Yes there is a newer version issued January 2018 in which section 7.4 has been amended and this is no longer there. That would explain why it is in the textbook which is what was puzzling me.
    https://qualifications.pearson.com/content/dam/pdf/A Level/Mathematics/2017/specification-and-sample-assesment/a-level-l3-mathematics-specification.pdf
     
  10. BG54

    BG54 New commenter

    Thanks, that's poor from Pearson, the previous issue (3) is still featured for download under the "Specification" tab.

    https://qualifications.pearson.com/en/qualifications/edexcel-a-levels/mathematics-2017.html
     
  11. adamcreen

    adamcreen Occasional commenter

    It's 13:15 now and the version on the link BG54 posted is definitely version 3, which is the correct one, with the amendments listed at the front
    So either they've fixed it or BG54 is in a different time zone!
     
  12. gainly

    gainly Lead commenter

    Actually on the link you (BG54) posted the specification is the newer one January 2018. There is a summary of changes at the beginning. Strangely it is also Issue 3. I agree it is poor to change the specification after just a month.
     
  13. BG54

    BG54 New commenter

    I have no idea what's going on, I'm sure I checked the content of that link just before I posted at 9.22am. Anyway, at least we can now be certain what is and isn't in the latest A-level spec. although I'm not sure why they made such a late change.
     
  14. BG54

    BG54 New commenter

    Tbf there are times when I'm on a different planet. ;-)
     
  15. briancant

    briancant Occasional commenter

    Well I didn't realize the specification had changed. Looking at it I'm not sure it has because it does say '...and inverse functions'. Which does include arcsin etc... They have only made the guidance more general.
     
  16. mr-celery

    mr-celery New commenter

    See attachment...
     

    Attached Files:

  17. adamcreen

    adamcreen Occasional commenter

    Since this thread has been resurrected, here's the reminder:
    students doing single Maths do not need to be able to differentiate invers trig functions.
    However, using implicit differentiation, they can be asked to differentiate x = sin y, and then write dy/dx in terms of x, so it's the same method, just without the initial line of the question ("y = arcsin x")
     

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