Question

Complex Numbers,

Can you please tell me why this equation is legitimate ?
https://www.dropbox.com/s/0w9df1skuikqvwl/Screenshot%202013-11-22%2004.37.20.jpg

Answer 1

\[e^{i\theta}=\cos(\theta)+i\sin(\theta)\]

Answer 2

if you don't understand what UnkleRhaukus said, I have a way to explain.
e^2 *e^(ipi) is a positive number, and - e^2 is a negative one. How can a positive number = a negative number? except 0, but e^ something never = 0

Answer 3

\[e^{i\pi}=\cos(\pi)+i\sin(\pi)\\\quad=-1+i(0)=-1\]

Answer 4

and from where is the minus?

Answer 5

kk got iy