(e^ix)^n=(e^ixn) & Trig identities

In summary, deriving trig identities from complex exponential expressions involves manipulating the expressions and identifying the identities. The trigonometric form can make it clearer, and the binomial theorem can be helpful. However, using too many odd identities at intermediate steps may cause confusion.
  • #1
complexhuman
22
0
ok...this was meant to be a fun problem :grumpy: but looks like I don't deserve to have fun!
How am I meant to derive trig identities like sin(x)cos^3(x) from some complex **** like [tex]\left( {e}^{{\it ix}} \right) ^{n}={e}^{{\it ixn}}[/tex]! I just don't get the idea! :cry:
 
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  • #3
complexhuman said:
ok...this was meant to be a fun problem :grumpy: but looks like I don't deserve to have fun!
How am I meant to derive trig identities like sin(x)cos^3(x) from some complex **** like [tex]\left( {e}^{{\it ix}} \right) ^{n}={e}^{{\it ixn}}[/tex]! I just don't get the idea! :cry:
It might be more clear in the trigonometric form where the equation is
[cos(x)+i sin(x)]^n=cos(n x)+i sin(n x)
so if you wanted to know
cos(3 x)=[cos(x)]^3-3cos(x)[sin(x)]^2
you could consider
[cos(x)+i sin(x)]^3=cos(3 x)+i sin(3 x)
so expand the left side find its real part and you have the identitiy
the binomial theorem can be helpful here
just be aware that using lots of odd identities at intermediate steps will mess things up
 
  • #4
thanks for the links inha. :smile:
 
  • #5
Thanks guys :)
 

1. What is the definition of (e^ix)^n?

The definition of (e^ix)^n is the result of raising the complex exponential number e^ix to the power of n. This means that the number e^ix is multiplied by itself n times.

2. How is (e^ix)^n different from e^(ixn)?

The difference between (e^ix)^n and e^(ixn) lies in the order of operations. In (e^ix)^n, the complex exponential number e^ix is raised to the power of n first, and then multiplied by itself n times. In e^(ixn), the complex exponential number is multiplied by n first, and then raised to the power of ix. This can result in different numerical values.

3. How can (e^ix)^n be simplified using trigonometric identities?

(e^ix)^n can be simplified using the trigonometric identity e^(ix) = cos(x) + i*sin(x). This means that (e^ix)^n can be written as (cos(x) + i*sin(x))^n. From there, the binomial theorem can be used to expand and simplify the expression.

4. What are the applications of (e^ix)^n in scientific calculations?

(e^ix)^n is commonly used in scientific calculations involving oscillations and waves, such as in electrical engineering, physics, and signal processing. It is also used in the study of complex numbers and their applications in various fields of science and mathematics.

5. Can (e^ix)^n be used to solve real-world problems?

Yes, (e^ix)^n can be used to solve real-world problems that involve oscillations and waves, such as in the analysis of electrical circuits and the behavior of electromagnetic waves. It is also used in the study of quantum mechanics and other branches of physics.

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