What Does x mean in euler's formula?

Question

Answer 1

x = an angle

if x= pi or 180 degrees

e^ipi = cospi + isinpi = -1 + 0 = -1

e^ipi = -1, which is a "famous" version of Euler's formula or identity

another surprise is taking the natural log of both sides to obtain

ipi = ln(-1)

while graphically there is no natural log of a negative number, with Euler's formula there is an imaginary solution: ln(-1) = i(pi)