# A level maths. Differentiation of arcsin (x)?

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

1. ### gainlyStar 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. ### briceanusNew commenter

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

gainly likes this.
3. ### gainlyStar commenter

Thank you for clearing that up.

4. ### briancantOccasional 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. ### briancantOccasional commenter

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

6. ### BG54Occasional 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. ### gainlyStar 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. ### BG54Occasional 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. ### gainlyStar 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. ### BG54Occasional 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

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. ### gainlyStar 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. ### BG54Occasional 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. ### BG54Occasional commenter

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

15. ### briancantOccasional 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-celeryNew commenter

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