Euler's formula
eiθ=cosθ+isinθ
Exponential form of complex number z
z=reiθ
Multiply z1=r1eiθ1 and z2=r2eiθ2
z1z2=r1r2ei(θ1+θ2)
Divide z2z1 in exponential form
r2r1ei(θ1−θ2)
cosθ in exponential form
21(eiθ+e−iθ)
sinθ in exponential form
2i1(eiθ−e−iθ)
arg(z1z2) equals
arg(z1)+arg(z2)
∣z1z2∣ equals
∣z1∣×∣z2∣
−1
e−iθ equals
cosθ−isinθ