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

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

Heres the Picture:

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

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

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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**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,564

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

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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