I met the following expression in a QM book:(adsbygoogle = window.adsbygoogle || []).push({});

[itex]

\frac{sin[(n+1/2)\pi+\epsilon]}{cos[(n+1/2)\pi+\epsilon]}=\frac{(-1)^n\cos(\epsilon)}{(-1)^{n+1}\sin(\epsilon)}

[/itex]

where [itex]

\epsilon << 1

[/itex]

No matter how hard I try (sine of sum, etc.), I can't see the intermediate steps to this result.

Please, help.

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# Trigonometric limit

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