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# derivative problem watch

1. derive the identity

(sech^2 x)/(1+tanh^2 x) = sech2x

and

sech x = (2e^x)/(e^2x +1)

help me out.i cant solve these.it is under principle of integral evaluation.thanks
2. Perhaps this isn't what you're looking for, but the first one can be done using the fact that , and , and by using Osborn's rule on a certain double-angle identity for cosine.

The second can be done from the definition
3. I don't see why you're talking about derivatives and integrals, as you don't need to use either.

We have, by definition:

Use these to prove the identities.
4. (Original post by tommm)
I don't see why you're talking about derivatives and integrals, as you don't need to use either.

We have, by definition:

Use these to prove the identities.
I have heard your decent at maths, just wondering have you studied any AEA maths? How hard did you find it compared to A-level (if you have studied it).
Also would you say it is harder than Step I or even Step II? How similar would it be to them?

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