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A lot rests against the top of a wall. The head of a person 6' tall just such touches the ladder. The person is 9' from the wall and 6' from the foot of the ladder. Find the height of the wall.

A lot rests against the top of a wall. The head of a person 6' tall just such touches-example-1

1 Answer

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When you have two triangles as given, they are similar triangles. It means that the ratio between corresponding sides is the same.

Corresponding sides are:

Side x (height of the wall) and the height of the person (6 feet)

Distance between the wall and the foot of the lader (6 feet + 9 feet= 15 feet) and distance between the person and the foot of the lader (6 feet)

Then, you have the next:


(x)/(6ft)=(15ft)/(6ft)

Solve for x:


\begin{gathered} x=6ft\cdot(15ft)/(6ft) \\ \\ x=15ft \end{gathered}Then, the height of the wall is 15 feet

A lot rests against the top of a wall. The head of a person 6' tall just such touches-example-1
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