Answer:
10.6 ft
Explanation:
to find the diagonal length of the stairway we can use the pythagorean theorem or a^2 + b^2 = c^2
6'4" is also 6 1/3' or 19/3'
8'6" is also 8 1/2' or 17/2'
now square them both
361/9 + 289/4
make them have the same denominator
1444/36 + 2601/36
add them
4045/36
take the square root
10.6000524 is your answer
10.6 ft