Question 200266
12^2+x^2=(x+4)^2
144+x^2=x^2+8x+16
8x=144-16
8x=128
x=128/8
x=16 ft. is the distance from the building to the foot of the ladder
16=4=20 ft. is the length of the ladder.
Proof:
12^2=16^2=20^2
144+1256=400
400=400