Answer:
4' - 9.64
Explanation:
Total rise = 2' - 7"
Total run = 3' - 9"
Converting to inches :
1' = 12" ; 1 feet = 12 inches
2' = 2 * 12 = 24"
3' = 3 * 12 = 36"
Total rise = 24" + 7" = 31"
Total run = 36" + 9" = 45"
Length of stringer = hypotenus
Hypotenus = √(total rise² + total run²)
Hypotenus = √(31² + 45²)
Hypotenus = 54.644304"
= 4' - 9.64"