(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Prove sin(x-iy) = sin(x) cosh(y) - i cos(x) sinh(y)

2. Relevant equations

3. The attempt at a solution

I tried to prove it by developing sinh into it's exponential form, but I get stuck.

sinh(x-iy) = [ e^{i(x-iy)}- e^{-i(x-iy)}] /2i

= [ e^{ix}e^{y}- e^{-ix}e^{-y}] /2i

This is where I get stuck. I can regroup the terms to get the following equation, but doesn't seem like the right direction.

= sinh(y+ix)/i

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# Homework Help: Proving an identity involving hyperbolic functions

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