21.44 feet
According to the question, we have the following information
Angle of elevation = 4.8degrees
Height off the ramp = 1.8 foot
Required
The minimum horizontal length for the ramp
The required sketch of the ramp is shown below:
From the diagram above, we can use the SOH CAH TOA identity to determine the value of horizontal length "x"
[tex]\tan \theta=\frac{\text{opposite}}{\text{adjacent}}=\frac{1.8}{x}[/tex]Substitute the given parameters
[tex]\begin{gathered} \tan 4.8^0=\frac{1.8}{x} \\ x=\frac{1.8}{\tan 4.8^0} \\ x=\frac{1.8}{0.08397} \\ x\approx21.44\text{fet} \end{gathered}[/tex]Therefore the minimum horizontal length for the ramp so it satisfies the angle requirement is approximately 21.44 feet