Math CentralQuandaries & Queries


Question from anna, a student:

How do you evaluate the integration of integration of cos (x^2+y^2) dx dy?

Hello Anna,
For this question, it is handy to convert to polar coordinates.
Recall that,

r2 = x2 + y2, x = r cosθ, y= r sinθ.

And that dx dy changes into r dr dθ.
Without knowing more about the region of integration, this is about all the help that can be given.
Hope this helps,

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