Answer: ~31.3
first use the pythagorean theorem. a^2+(40)^2=50^2.
simply. a+1600=2500. subtract 1600 from both sides. a^2=900.
square root both sides to get a= 30
then find how far the top of the ladder is from the ground once in its new position.
a^2+(39)^2=50^2.
simplify. a^2+1512=2500. subtract 1512 from both sides to get a^2=979.
square root both sides to get a=31.288975. round to the nearest tenth to get a=31.3