\int_0^\inftye^(-ax)\cos(bx)dx?
All I know is a/(a^2+b^2) , and you have to use the below limit four times.
\lim_(x->\infty)e^(-ax)=0
All I know is
2 Answers
Explanation:
Integrate by parts:
Now:
and
then:
Integrate by parts again:
Again for
and for
then:
The integral now appears on both sides of the equation and we can solve for it:
Explanation:
Using the de Moivre's identity
but
now if
Finally