Question

find all solutions for cos z = 2, z=x+iy?

Answer 1

2-iy = x

Answer 2

2-x/i = y

Answer 3

2-x/y = i

Answer 4

you need to start with
\[\frac{1}{2}(e^{iz}+e^{-iz})=2\]

Answer 5

then to
\[e^{iz}+e^{-iz}=4\] and then
\[e^{2iz}+4e^{iz}+1=0\] solve the quadratic equation in \(e^{iz}\)

Answer 6

typo i mean
\[e^{2iz}-4e^{iz}+1=0\]

Answer 7

ohh. ic. thx.

Answer 8

yw

Answer 9

cos never be 2 in maths

Answer 10

-1<cosx<1