Mathematics
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OpenStudy (unklerhaukus):
\[\int\cot (x)\cdot\text dx\]
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OpenStudy (unklerhaukus):
what is the easy way to do this?
mathslover (mathslover):
put cot x = cos x/ sin x
mathslover (mathslover):
yes please wait
OpenStudy (unklerhaukus):
\[\int\frac{\cos x}{\sin x}\text dx\]
OpenStudy (anonymous):
\[\ln \left| \sin(x)\right|\]
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OpenStudy (anonymous):
+C !
mathslover (mathslover):
\[\large{\int{\frac{cosx}{sinx}}dx}\]
\[\large{du = cos(x)dx}\]
right?
OpenStudy (unklerhaukus):
oh yeah,
mathslover (mathslover):
du = cos(x) and sin (x) = u
mathslover (mathslover):
\[\large{\int{\frac{cosx}{sinx}}=\int{\frac{du}{u}}}\]
Can u solve this integral now?
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mathslover (mathslover):
You will get : \(\large{ln|u| +C}\)
mathslover (mathslover):
u = sin x
OpenStudy (unklerhaukus):
\[\int \cot x \text dx \]\[=\int\frac{\cos x}{\sin x}\text dx\] \(u=\sin (x)\) \(\text du = \cos(x)\text dx\) \[=\int\frac{\text du}u\]\[=\ln |u|+c\]\[=\ln |\sin x|+c\]
mathslover (mathslover):
good work .. you got it @UnkleRhaukus
OpenStudy (anonymous):
you are not familiar with this ?!
\[\int\limits_{}^{}\frac{u'(x)}{u(x)}dx = \ln(\left| u(x) \right|+C\]
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mathslover (mathslover):
Great!!! ..
OpenStudy (unklerhaukus):
thanks mathslover
mathslover (mathslover):
@Neemo being familiar with that and being familiar with the proof are diff. things :)
OpenStudy (unklerhaukus):
yeah it makes sense now it just wasn't an obvious substitution
mathslover (mathslover):
best of luck ..
have to go now
bbye
thanks!!
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OpenStudy (unklerhaukus):
thank you