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Some trigonometric, exponential thing? 
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#1
Nov312, 04:44 AM

P: 378

How can we say:
f(x)=A'sin(kx)+B'cos(kx) or equivalently f(x)=Ae[itex]^{ikx}[/itex]+Be[itex]^{ikx}[/itex]?? How are these two equivalent knowing that e[itex]^{ix}[/itex]=cosx+isinx I don't get this? 


#2
Nov312, 05:11 AM

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#3
Nov312, 05:44 AM

P: 378

it would be: A(coskx +isinkx)+B(coskxisinkx)
which's (A+B)coskx+i(AB)sinkx .. A'coskx+iB'sinkx where's did the "i" go? 


#4
Nov312, 06:04 AM

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Some trigonometric, exponential thing?
i told you they won't both be real! 


#5
Nov1812, 03:11 AM

P: 378

Sorry, i didn't check the site from since, I had some connection difficulties.
So, my final question, can this be done? Is the exponential form an alternative for the known trigonometric one? And why do I use it? Why not keep it in trigonometric form. I am working on potential wells, free particles and so, if this information would help you answer my question. 


#6
Nov1812, 04:09 AM

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Hi M. next!
You use cos and sin, or real exponentials, if you're only interested in real solutions, 


#7
Nov1812, 04:44 AM

P: 378

Thanks, am grateful



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