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OpenStudy (anonymous):

Integrate!

OpenStudy (anonymous):

\[\LARGE \int\limits_{-a}^{+a} \sqrt{\frac{a-x}{a+x}}dx\]

OpenStudy (anonymous):

I tried putting x=acos2theta

OpenStudy (anonymous):

I am confused that WILL we change the limits?

hartnn (hartnn):

why did you put that substitution ? what function will u get after the substitution ?

OpenStudy (anonymous):

\[\large \int\limits \sin^2 \theta d \theta\]

hartnn (hartnn):

why i am i not getting the same... also, if you are changing dx to dtheta, then you MUST change the limits

OpenStudy (anonymous):

limits change hongi?

hartnn (hartnn):

if you found dtheta, then you must change limits too

OpenStudy (anonymous):

but after changing limits im getting weird results lol lower limit pi/2 upper 0 how is it possible?

hartnn (hartnn):

how is that weird :O

OpenStudy (anonymous):

is that integration? upper limit is generally>lower limits..how is this integration then we are not practically "Integrating"

OpenStudy (anonymous):

\[acos2\theta=-a=>\cos2 \theta=-1 =>2 \theta= \pi=>\theta=\frac{\pi}{2}\] how pi?

hartnn (hartnn):

\(\int \limits_a^b =-\int \limits_b^a \) pi/2 is correct

OpenStudy (anonymous):

upper is 0

hartnn (hartnn):

yeah limits are correct

OpenStudy (anonymous):

hello @hartnn

hartnn (hartnn):

abeee, idhar hi to hu

OpenStudy (anonymous):

..i dont think so

hartnn (hartnn):

i did say limits are correct...

hartnn (hartnn):

what the doubt ?

OpenStudy (anonymous):

integration answer will come -ve and wrong i tried it..

hartnn (hartnn):

the function sqrt (....) simplifies to tan theta ? right ?

OpenStudy (anonymous):

\[\int\limits \tan \theta \times -2a \sin 2 \theta d \theta=>- 4a \int\limits \tan \theta \sin \theta \cos \theta= -4a \int\limits \sin^2 \theta d \theta\]

OpenStudy (anonymous):

\[\frac{1}{2}(\theta-\sin \theta \cos \theta) ]_\frac{\pi}{2}^0\]

hartnn (hartnn):

-2a int 1-2cos2theta -2a (t - sin 2t) 0 to pi/2 2a (pi/2 - 0 ) a pi ?

OpenStudy (anonymous):

\[−2a (\frac{\pi}{2})=-a \pi\]

hartnn (hartnn):

mera to api aaya

OpenStudy (anonymous):

0 to pi/2 kaise kara? - hatake reverse limits?

hartnn (hartnn):

oops, yes, i get - api too

OpenStudy (anonymous):

:/

OpenStudy (anonymous):

hogaya api agaya..- lagakar change limits (-)(-)=+

hartnn (hartnn):

-2a int 1-2cos2theta -2a (t - sin 2t) pi/2 to 0 2a (pi/2 - 0 ) a pi this is what u did too, right ?

hartnn (hartnn):

i think yes, and you are correct, and we both now get api

OpenStudy (anonymous):

:D

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