- #1

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## Main Question or Discussion Point

I have big problems solving this integration:

[tex]

\int_{-a}^{a}\sqrt{a^2-x^2}e^{i(kx-wt)}dx

[/tex]

I did an substitution with:

[tex]

x=a*sin(u)

[/tex]

Which gave me:

[tex]

\int_{-{pi}/2}^{{pi}/2}a^2cos^2(u)e^{i(kasin(u)-wt)}du

[/tex]

But i don't know if that did it any better, cause i can't figure out how to go on from there. I've been told to try the substitution:

[tex]

v=a*sin(u)

[/tex]

But without any success... Please help me somebody!

[tex]

\int_{-a}^{a}\sqrt{a^2-x^2}e^{i(kx-wt)}dx

[/tex]

I did an substitution with:

[tex]

x=a*sin(u)

[/tex]

Which gave me:

[tex]

\int_{-{pi}/2}^{{pi}/2}a^2cos^2(u)e^{i(kasin(u)-wt)}du

[/tex]

But i don't know if that did it any better, cause i can't figure out how to go on from there. I've been told to try the substitution:

[tex]

v=a*sin(u)

[/tex]

But without any success... Please help me somebody!