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Friday, June 18, 2021

Cauchy integral formula

triple exponential

Triple exponential integral

We show the proof of the following integral: π0eecosxcossinxcos(ecosxsinsinx)dx=πe
On the way we will find this beautiful result: π0eeeix+eeeixdx=2πe
Proof π0eecosxcossinxcos(ecosxsinsinx)dx=π0eecosxcossinx[eiecosxsinsinx+eiecosxsinsinx2]dx=12π0eecosxcossinx+iecosxsinsinx+eecosxcossinxiecosxsinsinxdx=12π0eecosx(cossinx+isinsinx)+eecosx(cossinxisinsinx)dx=12π0eecosxeisinx+eecosxeisinxdx=12π0eecosx+isinx+eecosxisinxdx=12π0eeeix+eeeixdx=12π0[n=0(eeix)nn!+0(eeix)nn!]dx=12π0n=0(eeix)n+(eeix)nn!dx=12n=01n!π0(eeix)n+(eeix)ndx=12n=01n![π0(eeix)ndx+π0(eeix)ndx]=12n=01n![π0(eeix)ndx0π(eeix)ndx]=12n=01n![π0(eeix)ndx+0π(eeix)ndx]=12n=01n!ππ(eeix)ndx=12n=01n!γeznzidz(where γ(x)=eixx[π,π])=12n=01n!2π(Cauchy integral formula)=πe
π0eecosxcossinxcos(ecosxsinsinx)dx=πe
Corollary π0eeeix+eeeixdx=2πe

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