• May 2nd 2010, 12:21 PM
rhcp1231
Evaluate the indefinite integral. (Enter your answer in terms of cos function.)

http://www.webassign.net/cgi-bin/sym...pi%20t%29%20dt

so far i have:

u = 4$\displaystyle pi$t
du = $\displaystyle pi$dt

1/$\displaystyle pi$du = dt

once you subsitute it all back in i get a final answer of:

(1/$\displaystyle pi$)(cos4$\displaystyle pi$t)+c

but this is not correct....
where is my mistake?
• May 2nd 2010, 12:24 PM
Riyzar
Quote:

Originally Posted by rhcp1231
Evaluate the indefinite integral. (Enter your answer in terms of cos function.)

http://www.webassign.net/cgi-bin/sym...pi%20t%29%20dt

so far i have:

u = 4$\displaystyle pi$t
du = $\displaystyle pi$dt -> False

1/$\displaystyle pi$du = dt

once you subsitute it all back in i get a final answer of:

(1/$\displaystyle pi$)(cos4$\displaystyle pi$t)+c

but this is not correct....
where is my mistake?

$\displaystyle (4\pi*t)' = 4\pi$

Also note that$\displaystyle \int sin(u)du=-cos(u)+C$
• May 2nd 2010, 12:33 PM
rhcp1231
Quote:

Originally Posted by Riyzar
$\displaystyle (4\pi*t)' = 4\pi$

Also note that$\displaystyle \int sin(u)du=-cos(u)+C$

-1/pi(cos(pi*t))+c
correct?
• May 2nd 2010, 12:42 PM
skeeter
Quote:

Originally Posted by rhcp1231
$\displaystyle -\frac{\cos(4\pi t)}{4\pi} + C$