A ladder leans against a vertical wall. Upper End of the ladder is 8 m above the ground. When the lower end of the ladder is moved 2 m farther away from the wall, the other end of the ladder rests against the foot of the wall. The length of the ladder is:

17 m

By using the pythagoras theorem,

P² + B² = H²

8² + B² = A²

64 + B² = A²

&  A = 2 + B

64 + B² = (2 + B )²

64 + B² = 4 + B² + 4B 

4B = 60

B = 15

So, A = 15 +2 = 17 m

So length of ladder = 17 m