This technique requires an understanding and recognition of complex numbers.
Specifically Euler's formula:
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Recognize, for example, that the real portion:
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Given an integral of the general form:
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We can complexify it:
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With basic rules of exponents:
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It can be proven that the "real portion" operator can be moved outside the integral:
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The integral easily evaluates:
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Multiplying and dividing by (1-2i):
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Which can be rewritten as:
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Applying Euler's forumula:
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Expanding:
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Taking the Real part of this expression:
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So:
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