Q8 of 42 Page 220

A wire attached to vertically pole of height 18m is24m long and has a stake attached to other end. How far from the base of the pole should the stake be driven so that the wire will be taut?

Given, height of a pole is 18 and wire attached is 24m


Need to find the distance from the base to keep wire taut


⇒ Let AB be a wire and pole be BC


⇒ to keep the wire taut let it be fixed at A


⇒ AB2 = AC2 + BC2


⇒ 242 = AC2 + 182


⇒ AC2 = 242 + 182


⇒ AC2 = 576-324


⇒ = 252


⇒ AC = √ 252


= √(36 × 7)


= 6√ 7


Hence, the stake may be placed at a distance of 6√ 7m the base of pole


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