The answer would be:
20.9 ft
Here is why:
If you draw the scenario, (which is attached below) you can see that a right triangle is formed. The ramp length is the hypotenuse of the scenario. To solve for it, we can use the Pythagorean Theorem where:
[tex]c^{2}= a^{2} + b^{2}[/tex]
Where:
c = hypotenuse (Longest side)
a and b = legs of the triangle
Let's take our given and put it into the formula:
c = length of the ramp
a = 6ft
b = 20ft
[tex]c^{2}= (6ft)^{2} + (20ft)^{2}[/tex]
[tex]c^{2}= 36ft^{2}+ 400ft^{2}[/tex]
[tex]c^{2}= 36ft^{2}+ 400^{2}[/tex]
[tex]\sqrt{c^{2} } = \sqrt{436ft^{2}}[/tex]
[tex]c= 20.9ft[/tex]
Hope you get it!
