[tex]e^{ix}=cosx + isinx [/tex](adsbygoogle = window.adsbygoogle || []).push({});

I know this can be easily proven using the Taylor series, but I recall seeing a proof which doesn't use the Taylor series. I'm pretty sure it has something to do with derivatives, but the problem is I don't remember how it went and I can't find it anywhere. So if anyone knows it or has any idea of where to start could you let me know? Thanks.

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# Proof of complex exponential

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