For this case we have to define trigonometric relationships in rectangular triangles that:
The sine of an angle is given by the opposite leg to that angle on the hypotenuse of the triangle.
Then, according to the figure shown we have to:
![Sin (47) = \frac {x} {18}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/efh0tz0c2cwgdrbkdajxw6dzfiqxhgq5n7.png)
So, clearing the value of "x" we have:
![x = Sin (47) * 18\\x = 0.7314 * 18\\x = 13.16](https://img.qammunity.org/2020/formulas/mathematics/middle-school/w75pypc3722at28z7giyot8km8oo9frxjv.png)
We round and we have the value of "x" is:
![13.2 \ ft](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6nfz0gjbldtvulnmku4pnu7xxl523p0cj3.png)
Answer:
![13.2 \ ft](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6nfz0gjbldtvulnmku4pnu7xxl523p0cj3.png)