Answer:
Correct option is:
A. 486 units²
Step-by-step explanation:
We have to find the surface area of cube with side length 9 units
We know that surface area of cube is:
6s²
where s is the side of the cube
Here, s=9 units
Surface area=6×9×9
= 486 units²
Hence, Correct option is:
A. 486 units²
486 units²
Given:
s = 9 units
Let us find out the surface area of a cube.
The formula of the surface area of a cube is [tex]\boxed{ \ S = 6(s^2) \ }[/tex],
where s is the length of one of the sides.
[tex]\boxed{ \ S = 6(9^2) \ }[/tex]
[tex]\boxed{ \ S = 6(81) \ }[/tex]
[tex]\boxed{ \ S = 6 \times 81 \ }[/tex]
Thus, the surface area of the cube is 486 sq. units.
Notes:
From the formula for surface area, we make it s as a subject.
[tex]\boxed{ \ 6(s^2) = S \ }[/tex]
[tex]\boxed{ \ s^2 = \frac{S}{6} \ }[/tex]
[tex]\boxed{\boxed{ \ s = \sqrt{\frac{S}{6}} \ }}[/tex] ... Equation-1
The formula of the volume of a cube is [tex]\boxed{ \ V = s^3 \ }.[/tex]
Substitute Equation-1 into the volume formula.
[tex]\boxed{ \ V = \bigg( \sqrt{\frac{S}{6}} \bigg)^3 \ }.[/tex]
Thus, we have connected formulas of surface area with the volume of the cube.
Keywords: what is the surface area of the cube, the length of the cube, volume, 9 units, 486 units², 508 units², 729 units², 405 units², the formula
