Circular cosine is hyperbolic cosine on the imaginary axis: $\cos z=\cosh(iz)$.Suggest a slogan
For every \(z\in\CC\), \[ \cos(z) = \cosh(iz). \]
How is $\cos(z)$ written in terms of $\cosh$?
$\cos z = \cosh(iz)$
FF-AGEQ4
FF-AGEQ4
For every \(z\in\CC\), \[ \cos(z) = \cosh(iz). \]