Answer:
[tex]l \approx 15.455\,ft[/tex]
Step-by-step explanation:
The length of the ramp is computed with the help of the following trigonometric function:
[tex]\sin \theta = \frac{h}{l}[/tex]
[tex]l = \frac{h}{\sin \theta}[/tex]
[tex]l = \frac{4\,ft}{\sin 15^{\circ}}[/tex]
[tex]l \approx 15.455\,ft[/tex]