word problem

[BodybldgDoc]

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A 120 m trapping net stretched out into a 3-sided rectangular corral is used to front a flowing river. What value of widths (w), being parallel to the riverbanks, will provide the corral with largest capturing area?

How do we solve this?

 

[DailyDrivenTJ]

Since the net is made into the rectangular shape, there are going to be two equal sides(x) and one side(120-2x).

(120-2x)*x = Area of the net.

For the equation 120x-2x^2=0, 0 and 60 are the solutions and half way point between the 0 and 60 will give the maximum value for that equation.

Or you can use the calculus to find the first derivative the equation and find where it is equal to zero.

so the net should be casted so that it will make 60x30 meters.

 

[BodybldgDoc]

thanks TJ