Answer:
Part 3) [tex]SA=288\ cm^2[/tex]
Part 4) [tex]64\ cm^2[/tex]
Step-by-step explanation:
Part 3) Calculate the total surface area of three 4 cm cubes
we know that
The surface area of a cube is equal to the area of its six square faces
[tex]SA=6b^2[/tex]
so
The surface area of three cubes is equal to the area of its 18 square faces
[tex]SA=18b^2[/tex]
where
b is the length side of the square face
In this problem
[tex]b=4\ cm[/tex]
so
The surface area of three cubes is
[tex]SA=18b^2[/tex]
substitute the given value
[tex]SA=18(4)^2[/tex]
[tex]SA=288\ cm^2[/tex]
Part 4) How much surface area would be lost if you glued three 4-cm cubes together to make a rod that is three cubes long and one cube wide?
In this case the total surface area of the three glued 4-cm cubes is equal to the area of its 14 square faces
so
The surface area lost is equal to
[tex]18b^2-14b^2=4b^2[/tex]
substitute
[tex]4(4)^2=64\ cm^2[/tex]
