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October 14th, 2012, 06:37 PM   #1
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Find length of sides of quadrilateral; write equation

Hello all,

I have a seemingly simple question. I have a quadrilateral with sides (starting with the left side, moving clockwise)7-x), (x+2), (2x-1), (x-3).

a) write an equation for the perimeter and simplify: that's easy, and done. This ends up as 3x+5

b) Find the length of all sides. Using the result from above, 3x+5 = -5/3, and would give one of the sides a -negative answer. I assume one cannot have a negative length?

Your thoughts and help will be greatly appreciated.


David Dudek
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October 14th, 2012, 07:07 PM   #2
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Re: Find length of sides of quadrilateral; write equation

You've got an expression, 3x + 5, not an equation. The result of -5/3 assumes 3x + 5 = 0, when it should be 3x + 5 = P, where P is the perimeter. Using this we have

x = (P - 5)/3.

Can you continue from there?

Note: P must be less than 26 units. Do you see why?
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October 14th, 2012, 07:49 PM   #3
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Re: Find length of sides of quadrilateral; write equation

Originally Posted by David Dudek
(7-x), (x+2), (2x-1), (x-3).
side 7-x: x < 7
side x-3: x > 3
So x = 4 or 5 or 6
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