(a)
we are given
length of rectangle is 3cm
[tex]L=3cm[/tex]
width of rectangle is 4cm
[tex]W=4cm[/tex]
now, we can use area formula
[tex]A=L\times W[/tex]
we can plug values
[tex]A=4\times 3[/tex]
[tex]A=12 cm^2[/tex]
Let's assume side of square is 'a'
[tex]A=a^2[/tex]
we can set them equal
and then we can solve for a
[tex]a^2=12[/tex]
[tex]a=3.464cm[/tex]..........Answer
(b)
we are given
length of cuboid is 2cm
so, [tex]L=2cm[/tex]
width of cuboid is 4cm
so, [tex]W=4cm[/tex]
height of cuboid is 5cm
so, [tex]H=5cm[/tex]
now, we can find volume
[tex]V=L\times W\times H[/tex]
now, we can plug values
[tex]V=2\times 4\times 5[/tex]
[tex]V=40cm^3[/tex]
Let's assume edge of cube is 'a'
so, volume is
[tex]V=a^3[/tex]
now, we can set them equal
and then we can solve for a
[tex]a^3=40[/tex]
[tex]a=3.420cm[/tex]...........Answer