Hi,(adsbygoogle = window.adsbygoogle || []).push({});

How would I do the following:

Find all w in C, such that cos(z + w) = cos z, for all z in C.

Of course I would need to use the identity cos z = (e^iz +e^-iz)/2, but I have trouble finding w for all z.

Thank you

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Sin and cos in z

**Physics Forums | Science Articles, Homework Help, Discussion**