Question

The period of ${\cos h}(4x)$ is .

• A. $2\pi i$
• B. $\pi i$
• C. $\frac{\pi i}{2}$
• D. $2\pi$

Answer 1

Answer: (C)

$\frac{\pi i}{2}$

Answer 2

$\cosh(4x) = \cosh(2\pi i + 4x) = {\cos h}4\left( \frac{\pi i}{2} + x \right)$

∴ Period is $\frac{\pi i}{2}$.