Respuesta :

Answer:

The surface area of the cuboid is 42 sq.cm.

Step-by-step explanation:

The cuboid  is made of 3 unit cubes like the one to its left

Surface area of cube =[tex]6a^2[/tex]

Where a is the side of cube

We are given that surface area of cube is 18 sq.cm.

So, [tex]6a^2 = 18 \\a^2 = \frac{18}{6}\\a=\sqrt{\frac{18}{6}}\\a=\sqrt{3}[/tex]

Now these 3 cubes are joined together to form cuboid

So, Length of cuboid =[tex]\sqrt{3}+\sqrt{3}+\sqrt{3}=3\sqrt{3}[/tex]

Breadth of cuboid = [tex]\sqrt{3}[/tex]

Height of cuboid =[tex]\sqrt{3}[/tex]

Surface area of cuboid =[tex]2(lb+bh+hl)=2\left(3\sqrt{3}\cdot\sqrt{3}+\sqrt{3}\cdot\sqrt{3}+3\sqrt{3}\cdot\sqrt{3}\right)=42 cm^2[/tex]

Hence the surface area of the cuboid is 42 sq.cm.