Topic : applied maths question?

Two vertical walls, AB and CD are distance 2 metres apart.

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B D One ladder (1)rests at the foot of wall AB and leans against wall CD

Another ladder (2)rests at the foot of wall CD and leans against wall AB

If top of ladder (1) is 5.2 metres up wall CD, and top of ladder (2) is 3.8 metres up wall AB

At what height do they cross?

Simplest solution required

Posted: 27/02/2005 22:58:41
By: Math man
2.2m or have i missed the point.

Posted: 28/02/2005 11:47:49
By: snowed in and bored
Not that simple I suspect, I'll get a five year old to whom these things are so much easier to dp the calculus. And report back.

Posted: 28/02/2005 11:52:46
2.35m. Break it all down into triangles and then work out amgles and lenghts using tan, sine and cosine equations.

Posted: 01/03/2005 12:21:33
By: Q.E.D
QED - wrong again
How about - (AB x CD)/(AB + CD) = 5.2*3.8/9 = 2.19555

Posted: 01/03/2005 13:42:30
By: Sense or proportion
think I would take the lift!

Posted: 01/03/2005 14:20:41
By: interested
As the simplest solution is required, draw it on graph paper. I drew it on plain paper and got 2.2, given ladders are at least 0.05 thick, I think this is as accurate as you need. An took about 15 seconds to figure out.

Posted: 01/03/2005 16:14:15
By: Alan Fuller

Can I have a job like you lot have got, where no work needs to be done? Is the graph paper part of your package, Alan, or is it a taxable benefit in kind?


Posted: 01/03/2005 17:23:33
By: Chairman GGGGG
Come on GGGGG how many hours do you truly work? We all need diversion from defending the relm, or running multinationals.

Posted: 01/03/2005 18:01:32
Correct answer 2.195

Tis equivalent to two resistances in parallel

1/5.2 + 1/3.8 = 1/answer

0.193 + 0.263= 0.456

1/0.456 = 2.195

Posted: 01/03/2005 18:21:27
By: Math Man
Seems like 2.195 has it.

Posted: 01/03/2005 18:23:18
Ok, some us us are still working.

Quickest one to answer if the walls are not 2 meters apart but 2 miles apart (note change to imperial). If you got that in, then what is the answer if the walls are infinity apart?

Posted: 01/03/2005 21:07:57
By: Alan Fuller
same answer

Posted: 01/03/2005 23:50:45
By: Math Man
And thre proof in the infinite case is ......

Posted: 02/03/2005 11:36:25
By: Alan Fuller


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