Question Number 103481 by mohammad17 last updated on 15/Jul/20

prove that (cos((nθ)/5)+isin((2nθ)/(10)))^5 −(1/e^(inθ) )=2sin(nθ) ?

Answered by Dwaipayan Shikari last updated on 15/Jul/20

e^(nθi) −e^(−inθ) =2sin(nθ)  (e^(((nθ)/5)i) )^5 =e^(nθi)      {cosnθ+isinnθ−cosnθ+isinnθ=2isinnθ

Commented bymohammad17 last updated on 15/Jul/20

thank you sir