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1. How to do this?

Any way to do this using the methods in the C4 edexcel book?
2. Re: How to do this?
(Original post by sabre2th1)

Any way to do this using the methods in the C4 edexcel book?
use a trig identity to get

Now, use quotient rule to show that

From there, it should be obvious....
Last edited by latentcorpse; 17-06-2012 at 12:39.
3. Re: How to do this?
(Original post by latentcorpse)
use a trig identity to get

Now, use quotient rule to show that

From there, it should be obvious....

When you changed to cosec you did not mean to put 1/it
4. Re: How to do this?
(Original post by latentcorpse)
use a trig identity to get

Now, use quotient rule to show that

From there, it should be obvious....

(Original post by TenOfThem)
When you changed to cosec you did not mean to put 1/it
I've got it I think:

Cos 2x = 1-2Sin2x

therefore Cos 4x = 1-2Sin22x

therefore 1-Cos4x = 2Sin22x

therefore 1/(2Sin22x) = 2(cosec22x)

the integral of 2(cosec22x) = -4cot2x

Is the above right?
Last edited by sabre2th1; 17-06-2012 at 18:51.
5. Re: How to do this?
(Original post by sabre2th1)
I've got it I think:

Cos 2x = 1-2Sin2x

therefore Cos 4x = 1-2Sin22x

therefore 1-Cos4x = 2Sin22x

therefore 1/(2Sin22x) = 2(cosec22x)

the integral of 2(cosec22x) = -2cot2x

Is the above right?
You have 2 when it should be 1/2
6. Re: How to do this?
(Original post by TenOfThem)
You have 2 when it should be 1/2
Where? (I edited it several times in a row, so I might have corrected it just after you posted)

Thanks
7. Re: How to do this?
(Original post by sabre2th1)
Where? (I edited it several times in a row, so I might have corrected it just after you posted)

Thanks
8. Re: How to do this?
(Original post by TenOfThem)
Oh! I can spot it now! Thanks