Please help...

A man has 40 meters of fencing material. What are the Dimensions of the largest recangular pen which he can enclose? What is the maximum area?

Thank you!

Printable View

- February 18th 2008, 11:02 PMIlovemath123Dimensions of a rectangle
Please help...

A man has 40 meters of fencing material. What are the Dimensions of the largest recangular pen which he can enclose? What is the maximum area?

Thank you! - February 18th 2008, 11:10 PMCaptainBlack
Let the dimensions of pen be a x b then as the perimiter is 40m we have:

2a+2b=40

or:

b=20-a,

so now the area of the pen is:

A=a(20-a)

and the maximum of a quadratic occurs midway between its roots, so the

maximum area occurs when a=10m, but then b=10 and the pen is a square of

area 100m^2.

RonL