In this triangle, the ratio \(\dfrac {\text{opposite}}{\text{hypotenuse}}\) is equal to the sine of \(50 \degree\text{,}\) or

\begin{equation*}
\sin (50\degree) = \dfrac {\text{opposite}}{\text{hypotenuse}}
\end{equation*}

We use a calculator to find an approximate value for the sine of \(50 \degree\text{,}\) filling in the lengths of the hypotenuse and the opposite side to get

\begin{equation*}
0.7660 = \dfrac {x}{18}
\end{equation*}

We solve for \(x\) to find

\begin{equation*}
x = 18(0.7660)=13.788
\end{equation*}

To two decimal places, the length of the opposite side is 13.79 centimeters.