A guy wire attached to a vertical pole of height 18 m is 24 m long and has a stake attached to the other end. How far from the base of the pole should the stake be driven so that the wire will be taut?

Let AC = 18 m be the pole. BC = 24 m is the length of a guy wire and is attached to stake B.
∴ In △ABC
By Pythagoras theorem, BC² = AB² + AC²
∴ 24² = AB² + 18²
⇒ AB² = 576 − 324 = 252
∴ AB = 6√7 m
Hence, the stake has to be 6√7 m from base A.