# Homework Help: Find length of sides of quadrilateral; write equation

1. Oct 14, 2012

### David Dudek

1. The problem statement, all variables and given/known data

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?

2. Relevant equations

P = (7-x)+(x+2)+(2x-1)+(x-3)
=3x+5

x = -5/3?

3. The attempt at a solution

If x=-5/3, then;
P=(7-5/3)+(5/3+2)+(2x5/3-1)+(5/3-3)
=5 1/3 + 3 2/3 + 21/3 + -1 1/3

2. Oct 14, 2012

### LCKurtz

That isn't an equation of anything. Nothing you have written so far is an equation because equations have an = sign and two sides.

I can't make sense of any of that. You need to find where the sides intersect (the vertices) and use the distance formula to calculate the perimeter.

3. Oct 15, 2012

### David Dudek

Hi,

thanks for taking the time to respond.

I have spent a couple of days looking at this problem and have just discovered that a vital bit of information was there the whole time: the perimeter is 23cm!

Problem solved.

Thanks

4. Oct 15, 2012

### LCKurtz

Really?? That's pretty amazing. Given that the expressions above all should have "y =" on their left sides, those lines don't even form a quadrilateral.