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Cos(x) = cosh(x)? 
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#1
Mar1211, 07:15 AM

P: 13

1. The problem statement, all variables and given/known data
2. Relevant equations from the identities found on the internet: [tex]cos(x)=\frac{(e^{ix}+e^{ix})}{2}[/tex] and [tex]cosh(x)=\frac{(e^{x}+e^{x})}{2}[/tex] 3. The attempt at a solution Assuming for the definition of cosh(x), if we take x as being equal to (ix), then surely this shows that cosh(x)=cos(x)? Can someone explain why this is wrong please? because i can't see it 


#2
Mar1211, 07:30 AM

Sci Advisor
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Thanks
P: 25,246

It shows cosh(ix)=cos(x), not cosh(x)=cos(x). There's nothing wrong with that.



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