Answer:
The dimensions are:
l = 2*1.96 = 3.92 yd
h = 5/(1.96)² = 1.30 yd
w = 1.96 yd
Step-by-step explanation:
The volume is given by:
[tex]V=l*w*h[/tex]
Where:
We know that l = 2w, so we have:
[tex]V=2w^{2}*h[/tex]
[tex]10=2w^{2}*h[/tex]
[tex]5=w^{2}*h[/tex] (2)
Now, the surface of this parallelepiped is:
[tex]S=2wh+2lh+lw[/tex]
Using l = 2w:
[tex]S=2wh+4wh+2w^{2}[/tex]
Using (2) we obtain the surface equation in terms of w.
[tex]S=2w\frac{5}{w^{2}}+4w\frac{5}{w^{2}}+2w^{2}[/tex]
[tex]S=2\frac{5}{w}+4\frac{5}{w}+2w^{2}[/tex]
We need to take the derivative with respect to w to minimize the surface area.
[tex]S=2\frac{5}{w}+4\frac{5}{w}+2w^{2}[/tex]
[tex]S=\frac{30}{w}+2w^{2}[/tex]
[tex]\frac{dS}{dw}=-\frac{30}{w^{2}}+4w[/tex]
Now, let's equal it to zero.
[tex]0=-\frac{30}{w^{2}}+4w[/tex]
[tex]\frac{30}{w^{2}}=4w[/tex]
[tex]w^{3}=\frac{30}{4}[/tex]
[tex]w=1.96\: yd[/tex]
So, l = 2*1.96 = 3.92 yd and h = 5/(1.96)² = 1.30 yd
Therefore, the dimensions are:
l = 2*1.96 = 3.92 yd
h = 5/(1.96)² = 1.30 yd
w = 1.96 yd
I hope it helps you!
