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

I am in the process of doing a physics problem with a differential equation that has the form:

y = Acos(kx) + Bsin(kx)

According to my notes, this can also be written as y =Ae^{jkx}+ Be^{-jkx}, unfortunately I just don't see how to write the original equation like that.

2. Relevant equations

3. The attempt at a solution

I know that cos(x) = 1/2[ e^{jx}+ e^{-jx}]

sin(x) = 1/(2j) [ e^{jx}- e^{-jx}]

I can almost see how you would get it for the cos(kx) term:

Since Real { cos(kx) + j sin(kx) } = e^{jkx}using Euler's identity.

But for sine, I am stumped.

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# Homework Help: Cos/Sin to Exponential

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