Maximize the Area

P=2W+L=40——->L=40-2W

A=W*L= W*(40-2W)=40W-2W^2

W=-40/-4=10

P=2W+L=40—–>20+L=40—->L=40-20=20

L=20ft

W=10ft ——>A=200 sq ft

A=-2W+40W

40 ÷ 4=10

L=40-2W=40-2(10)=20

10*20=200 ft sq

W                                                                            W

L

2W + L = 40

L= 40–2w

A (W)= W(20–2W)                          –2W2 +40W =0

-b         = —40       =        40         = 10

2a           –2(2)                10

A (10) 10(40-2(10) ) = 10( 20  ) = 200m

20 ft :-))

Dimensions are…

Sides: 10ft on each side

Length parallel to the river is 20ft.