Hi all, I need help integrating: intg ((e^t)*cos(n*t))dt I have tried integrating by parts but it seemed like it just got more complicated. I know there is a theroem but i am not allowed to use it. Thanks in advance, ArTiCk
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You actually integrate by parts twice and end up with a multiple of intg ((e^t)*cos(n*t))dt on both sides. Combine these ans solve In both cases let u = e^t to get started. Let me know if it works out
Originally Posted by ArTiCK Hi all, I need help integrating: intg ((e^t)*cos(n*t))dt I have tried integrating by parts but it seemed like it just got more complicated. I know there is a theroem but i am not allowed to use it. Thanks in advance, ArTiCk $\displaystyle \int e^t \cos(nt)\; dt= \text{Re}\left\{ \int e^t e^{i n t}\; dt\right\}=\text{Re} \left\{\int e^{t(1+in)}\;dt\right\}$ CB
Heckuva lot easier than my approach
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