Answer
21.44 feet
Explanations:
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"

Substitute the given parameters

Therefore the minimum horizontal length for the ramp so it satisfies the angle requirement is approximately 21.44 feet