Hi friends. I have encountered three equations that I need to find three variable An, Bn, Cn. First two are easy to handle but third one includes multiplication of infinite series(fourier series).(adsbygoogle = window.adsbygoogle || []).push({});

First two are like:

Third equation is this:

Dm is known but in order to derive a general solution we behave as if it is not known. Therefore expressions of An, Bn, Cn may include Dm. Because I can not handle 3rd equation I cant find the soulution for An, Bn and Cn. How can I deduce an equation like first two from third equation? Can we make use of orthonality principle? Any idea? Thanks in advance.

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# How to handle this type of equations?

Can you offer guidance or do you also need help?

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