Answer
sinh x = $\frac{4}{3}$
Work Step by Step
Since x $\gt$ 0, we can say that sinh x = $\sqrt{ (cosh^{2}x - 1)}$
Substitute cosh x = $\frac{5}{3}$ to get
sinh x = $\sqrt{ (\frac{5}{3}^{2}-1)}$ = $\sqrt {(\frac{25}{9}-1)}$ = $\sqrt{ (\frac{25-9}{9})}$ = $\sqrt {\frac{16}{9}} = \frac{4}{3}$
