An 18m long ladder is leaning against the wall of a building. the top of the ladder reaches a window 11m above ground. if the ladder is tilted in the opposite direction, without moving its base, the top of the ladder can reach a window in another building that is 7 m above ground. How far apart, to the nearest metre, are the two buildings.

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Let us say;

Distance from ladder base to building 1 = x

Distance from ladder base to building 1 = y

Then the distance between buildings will be x+y

According to Pythagorean law we can say;

`18^2 = x^2+11^2 -----(1)`

`18^2 = y^2+7^2 -----(2)`

From (1) we get `x = sqrt(18^2-11^2) = 14.25m`

From (2) we get `y = sqrt(18^2-7^2) = 16.58m`

So the distance between buildings`= x+y= 14.25+16.58 = 30.83m`

*Distance between two buildings is 30.83m*

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