The formula [tex]$s=\sqrt{\frac{SA}{6}}$[/tex] gives the length of the side, [tex]$s$[/tex], of a cube with a surface area, [tex][tex]$SA$[/tex][/tex]. How much longer is the side of a cube with a surface area of 1,200 square inches than a cube with a surface area of 768 square inches?

A. [tex]$\sqrt{2}$[/tex] in.
B. [tex]$2\sqrt{2}$[/tex] in.
C. [tex][tex]$4\sqrt{2}$[/tex][/tex] in.
D. [tex]$36\sqrt{2}$[/tex] in.



Answer :

To determine how much longer the side of a cube with a surface area of 1,200 square inches is compared to a cube with a surface area of 768 square inches, we will follow these steps:

1. Calculate the side length of the cube with a surface area of 1,200 square inches:

We start by applying the formula [tex]\( s = \sqrt{\frac{SA}{6}} \)[/tex].

For [tex]\( SA = 1200 \)[/tex] square inches:
[tex]\[ s_1 = \sqrt{\frac{1200}{6}} = \sqrt{200} \approx 14.142135623730951 \][/tex]

2. Calculate the side length of the cube with a surface area of 768 square inches:

Again, applying the formula [tex]\( s = \sqrt{\frac{SA}{6}} \)[/tex].

For [tex]\( SA = 768 \)[/tex] square inches:
[tex]\[ s_2 = \sqrt{\frac{768}{6}} = \sqrt{128} \approx 11.313708498984761 \][/tex]

3. Find the difference in side lengths:

Subtract the side length of the cube with [tex]\( SA = 768 \)[/tex] square inches from the side length of the cube with [tex]\( SA = 1200 \)[/tex] square inches.
[tex]\[ \Delta s = s_1 - s_2 = 14.142135623730951 - 11.313708498984761 \approx 2.82842712474619 \][/tex]

4. Interpret the difference in terms of the given options:

The approximate value [tex]\( 2.82842712474619 \)[/tex] corresponds to [tex]\( 2\sqrt{2} \)[/tex]:

[tex]\[ 2\sqrt{2} \approx 2 \times 1.414213562 = 2.828427124 \][/tex]

Therefore, the side of the cube with a surface area of 1,200 square inches is [tex]\( 2\sqrt{2} \)[/tex] inches longer than the side of the cube with a surface area of 768 square inches.

The correct answer is:
[tex]\[ \boxed{2 \sqrt{2} \text{ in.}} \][/tex]