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Tom
Lv 6
Tom asked in Science & MathematicsMathematics · 1 decade ago

Impossible Math Question?-?

An alley with high wall on both sides has a 40 foot ladder leaning from the left wall to the right wall and a 30 foot ladder leaning from the right wall to the left. They cross 10 feet above the ground. How wide is the alley?

3 Answers

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  • 1 decade ago
    Favorite Answer

    The answer is 26 ft

    It looks like a really fancy similar triangles problem. But I cheated and used a drafting program to figure it out.

    Source(s): Microstation
  • 1 decade ago

    Here's a start. Sorry, but I've run out of time.

    Let's call the width of the alley x.

    The angle formed by the 40 foot ladder at the base is F (for Forty).

    The angle formed by the 30 foot ladder at the base is T (for Thirty).

    cos(F) = x/40

    cos(T) = x/30

    F = arccos(x/40)

    T = arccos(x/30)

    The ladders meet above a point that is y feet across the alley at a height of 10 feet.

    tan(F) = 10/y

    tan(T) = 10/(x - y)

    y = 10/tan(F)

    x - y = 10/tan(T)

    x = 10/tan(F) + 10/tan(T)

    x = (10tan(T) + 10tan(F)) / tan(T)tan(F)

  • 1 decade ago

    Idk , I'm gonna take a wild guess:

    60!

    I don't think this is impossible though - watch, some smart person is gonna prove all of us wrong that this is an impossible question...

    Source(s): Meh.
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