Cosine gone mad!

Algebra Level 3

If $x$ is a complex number, is this possible that $\cos x=3$ ?

Yes No

1 solution

Yash Dev Lamba
Feb 26, 2016

For example,

Let $x = i \ln (3 + \sqrt8)$

$\cos(x) = \frac{ \big(e^{ix} + e^{-ix}\big) }{2}$

$\displaystyle \Rightarrow \cos(x) = \frac{ (3+ \sqrt8) ^{-1} + (3 + \sqrt8)}{2}$

$\displaystyle \Rightarrow \cos(x) = \boxed{3}$

Could you please solve sin x=2?

Puneet Pinku - 4 years, 8 months ago