# Co-ordinate geometry minimum problem?

• May 8th 2013, 02:43 AM
iamapineapple
Co-ordinate geometry minimum problem?
The area of a rectangular block of land is 1000m2. If its length is x metres, find the block's dimensions if the perimeter is a minimum?

I have to solve the problem using a composite graph and finding its minimum rathert than using calculus. It would be appreciated if you could help me as I'm really not sure how to approach this :)

- iamapineapple
• May 8th 2013, 03:09 AM
MarkFL
Re: Co-ordinate geometry minimum problem?
Letting $x$ be the length, I would then let $y$ be the width, $A$ be the area, and $P$ be the perimeter.

Can you give the area and perimeter in terms of $x$ and $y$?
• May 8th 2013, 03:32 AM
iamapineapple
Re: Co-ordinate geometry minimum problem?
Thank you, I am so silly. I got to the stage of making an equation for the perimeter but broke down because I didn't know what to let it equal to (i.e. thanks to you, I just let it equal P and then subbed values)!

Thanks, I got the (easy) answer!
• May 8th 2013, 08:49 PM
ibdutt
Re: Co-ordinate geometry minimum problem?
Alternatively you can go as under: