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## #1 2006-02-27 02:43:47

johny
Member
Registered: 2005-11-19
Posts: 34

### Same Problem!!!!!

Well this question has been posted previously, but the previous one was inaccurate and this one has changed values.

A Lorry has a downwards wiping windscreen Wiper on a 40cm long metal arm. The rubber wiper part is at the end of the arm and is an articulate double module that alters in length during motion. The rubber alters between 30cm and 20cm, during a wiping "sweep" of the glass.

The full angle of the sweep is 60 degrees.

The bottom end of the rubber follows a path according to the equation

y = 1/30x (x-10* square root of 3)

The upper end of the rubber follows a path according to the equation:

y = 1/15 (x-5*square root of 3)^2 + 25

And we need to calculate the area of glass cleared in one full sweep of the arm.

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## #2 2006-02-27 02:47:57

johny
Member
Registered: 2005-11-19
Posts: 34

### Re: Same Problem!!!!!

Heres the Picture:

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## #3 2006-02-27 05:12:27

Ricky
Moderator
Registered: 2005-12-04
Posts: 3,791

### Re: Same Problem!!!!!

Oy, here we go again

"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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## #4 2006-02-28 02:26:17

johny
Member
Registered: 2005-11-19
Posts: 34

### Re: Same Problem!!!!!

Comeon people i seriously need help!!!!! Its the last time i will ever ask .......Ricky ur help will be appreciated, i know u know this pretty well, so whenever u find time post a reply. Thanks

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## #5 2006-02-28 07:17:40

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,588

### Re: Same Problem!!!!!

johny, if you can come up with the four (x,y) positions that are the
corners of this curved quatrilateral, then we can procede.
By you coming up with these (x,y) positions where the 60 degrees
works, this will further explain the problem, so there is no
uncertainty as to what you need because the we can draw
straight lines for those two sides of the shape.  So get to work and
report back to us.

igloo myrtilles fourmis

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## #6 2006-02-28 09:07:53

Ricky
Moderator
Registered: 2005-12-04
Posts: 3,791

### Re: Same Problem!!!!!

johny, I was just in a rush.  Of course we'll help you.  That was more of a joke, but I forgot things like that don't come across well with plain text.

I'll be making a post on this later tonight.

"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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