The pasture must contain 405000 square meters. What dimensions will require the least amount of fencing if none is needed by the river.

Question

One side of the fencing is adjacent to a river. 

     River

   |             |   

Y |             |  y

   |_______|

        X

Answer 1

A = 405000

405000 = L * W

 

405000/L = W

 

F = 2L + W

 

F = 2L + 405000/L

 

F = 2 - 405000/ L²

 

0 = 2 - 405000/L²

 

2 = 405000/L²

 

L² = 202500

 

L = 450 meters

 

405000 = 450 * W

 

W = 900 Meters

 

Don't forget to substitute L and W for Y and X.