- #1
DiracPool
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Hello. Please tell me how do I derive:
cos(θ)=1/2 ([itex]e^{iθ}[/itex]+[itex]e^{-iθ}[/itex])
from:
[itex]e^{iθ}[/itex]=cos(θ) + isin(θ)
as well as:
sin(θ)=1/2i ([itex]e^{iθ}[/itex]-[itex]e^{-iθ}[/itex])
I can't figure it out...for example, where does the 1/2 come from? Thank you
cos(θ)=1/2 ([itex]e^{iθ}[/itex]+[itex]e^{-iθ}[/itex])
from:
[itex]e^{iθ}[/itex]=cos(θ) + isin(θ)
as well as:
sin(θ)=1/2i ([itex]e^{iθ}[/itex]-[itex]e^{-iθ}[/itex])
I can't figure it out...for example, where does the 1/2 come from? Thank you