Answer:
7.6158 feet
Step-by-step explanation:
The rise and run form the shorter sides of a right triangle with the hypotenuse as the surface (see figure)
Hypotenuse (surface length) is given by the Pythagorean formula
[tex]c = \sqrt{a^2 + b^2}[/tex] where c is the hypotenuse and a, b the shorter sides
Here
[tex]\sf c = \sqrt{7^2 + 3^2} = \sqrt{49 + 9} = \sqrt{58} = 7.6158\;feet[/tex]