Question 520390: A rectangular field is fenced in by using a river as one side. If 1800m of fencing are used for the 385,000m^2 field, find its dimensions. Answer by solver91311(24713) (Show Source):
If one side uses the river, then the formula for the Perimeter fence is:
(as opposed to where all 4 sides are fenced)
The area is still
Solve the perimeter equation for
And substitute into the Area equation:
Put the quadratic into standard form:
Plug in your given values for the perimeter and area, and then solve the quadratic. It factors, but with these big numbers you might be better off using the quadratic formula with your calculator. You'll get two roots -- one has the short side on the river and one has the long side on the river.
John
My calculator said it, I believe it, that settles it
