euler identity

[zamri]

Hi, i seem to forgot how to simplify e^i*theta + e^-i*theta, the answer should be 2cos(theta). Can someone help me understand it to the steps.
thanks​

 

[Deleted member 4993]

Hi, i seem to forgot how to simplify e^i*theta + e^-i*theta, the answer should be 2cos(theta). Can someone help me understand it to the steps.
thanks​

e^iΘ = cos(Θ) + i*sin(Θ)

Now continue....

 

[zamri]

yap, i know that part...only when added up ..how to sum it up to get the final answer....thanks

 

[Oaky]

\(\displaystyle e^i^\theta = cos (\theta) + isin(\theta)\)
\(\displaystyle e^-^i^\theta = cos (\theta) - isin(\theta)\)

And adding the two gives...?

 

[zamri]

thanks a lot...