Answer:
Dimensions: 150 m x 150 m
Area: 22,500m²
Step-by-step explanation:
Given information:
- Rectangular field
- Total amount of fencing = 600m
- All 4 sides of the field need to be fenced
Let [tex]x[/tex] = width of the field
Let [tex]y[/tex] = length of the field
Create two equations from the given information:
Area of field: [tex]A= xy[/tex]
Perimeter of fence: [tex]2(x + y) = 600[/tex]
Rearrange the equation for the perimeter of the fence to make y the subject:
[tex]\begin{aligned} \implies 2(x + y) & = 600\\ x+y & = 300\\y & = 300-x\end{aligned}[/tex]
Substitute this into the equation for Area:
[tex]\begin{aligned}\implies A & = xy\\& = x(300-x)\\& = 300x-x^2 \end{aligned}[/tex]
To find the value of x that will make the area a maximum, differentiate A with respect to x:
[tex]\begin{aligned}A & =300x-x^2\\\implies \dfrac{dA}{dx}& =300-2x\end{aligned}[/tex]
Set it to zero and solve for x:
[tex]\begin{aligned}\dfrac{dA}{dx} & =0\\ \implies 300-2x & =0 \\ x & = 150 \end{aligned}[/tex]
Substitute the found value of x into the original equation for the perimeter and solve for y:
[tex]\begin{aligned}2(x + y) & = 600\\\implies 2(150)+2y & = 600\\2y & = 300\\y & = 150\end{aligned}[/tex]
Therefore, the dimensions that will give Tanya the maximum area are:
150 m x 150 m
The maximum area is:
[tex]\begin{aligned}\implies \sf Area_{max} & = xy\\& = 150 \cdot 150\\& = 22500\: \sf m^2 \end{aligned}[/tex]
