How can you use trigonometric functions to simplify  4 e^( ( 5 pi)/3 i )  into a non-exponential complex number?

$4 \left[\cos \left(\frac{5 \pi}{3}\right) + i \sin \left(\frac{5 \pi}{3}\right)\right]$
using the relationship : ${e}^{i \theta} = \cos \left(\theta\right) + i \sin \left(\theta\right)$