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Mathematics 22 Online
OpenStudy (anonymous):

Definite Integral HELP!!!

OpenStudy (anonymous):

OpenStudy (anonymous):

Correct Me If I am wrong.If not GIve Me the answer!!

OpenStudy (anonymous):

@Fifciol @amistre64 Help

OpenStudy (anonymous):

Is it correct??

OpenStudy (amistre64):

you can dbl chk by taking the derivative to see if you get back to the results

OpenStudy (anonymous):

Really need the answer!!

OpenStudy (amistre64):

you need to develop confidence in your work too; take the derivative of what you got, does it produce the original setup?

OpenStudy (anonymous):

Thats not my prob .My ans doesnt match with the given ans!!

OpenStudy (amistre64):

whats the given answers, you might need to simplify it

OpenStudy (anonymous):

Its 2(sqrt2-1)

OpenStudy (anonymous):

I get sqrt2

OpenStudy (anonymous):

use the identity: cosx= 2 cos^2(x/2) - 1 so the denominator becomes: 1+ 2cos^2(x/2)- 1 = 2cos^2(x/2) and the integral is reduced to: (1/2) ∫ sec^2(x/2) dx Let u=(x/2) ==> du= (1/2) dx so the integral becomes: (1/2) ∫ sec^2(u) dx = ∫ sec^2(u) du = tan u +c = tan(x/2) Then just plug in the integration limits and boom you are done!

OpenStudy (amistre64):

csc 0 is undefined since its 1/0 1/(1+cos) (1-cos)/sin^2 csc^2 - cotcsc -cot + csc does seem reasonable if ive remembered my derivatives ... but then csc is still troubled, might have to take the limit

OpenStudy (anonymous):

The formulas are a'ight ,my method isn't ,I guess!!

OpenStudy (amistre64):

sin = 0 at 0, so we would have to take the limits of: csc(x)-cot(x)-csc(pi/2)+cot(pi/2), as x to 0

OpenStudy (anonymous):

But in tan(x/2) case,wont u get ans as 1??

OpenStudy (amistre64):

the answer is 1, which is what you get when you do the limit ....

OpenStudy (anonymous):

But give ans is 2(sqrt2-1)!!!

OpenStudy (anonymous):

Must be a typo ,I guess!!

OpenStudy (anonymous):

Thanks again!!

OpenStudy (amistre64):

youre welcome

OpenStudy (anonymous):

But can u tell me the ans u get by applying my method.....Pls

OpenStudy (amistre64):

by applying your results:\[\left.csc(x)-cot(x)~\right|_{0}^{pi/2}\]since 0 is produces an undefined value for csc, we have to limit it up to zero:\[\lim_{a\to 0}\left.csc(x)-cot(x)~\right|_{a}^{pi/2}\]

OpenStudy (anonymous):

And dat gives us??

OpenStudy (anonymous):

1??

OpenStudy (amistre64):

of course

OpenStudy (anonymous):

Oh....Now I get it.Thank U very very much.Ur an awesome Helper.......!!Cheers!!

OpenStudy (amistre64):

yw

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