Question

2 cubes each of volume 64 cm^3 are joined end to end. Find the surface area of the resulting cuboid.​

Answer 1

Answer:

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Given, volume of each cube is 64 cm³

⇒s³=64

⇒s=∛64

⇒s=4 cm.

When two cubes are joined , 

the length of the resulting cuboid(l) = side + side = 4+4 = 8 cm

its breadth(b) = side = 4cm

And its height(h) = side = 4cm

Total surface area of a cuboid = 2(lb+bh+hl)

⇒TSA=2[(8)(4)+(4)(4)+(4)(8)]

⇒TSA=2(32+16+32)

⇒TSA = 2(80)

⇒TSA = 160 cm²

∴ The surface area of the resulting cuboid is 160 cm².

Answer 2

a^3 = 64

a=4

edge of each cube is 4 cm

Surface area = 2(lb+bh+hl)

now length will be 2a=8

breadth will be a=4

height will be a

so area = 2(2a^2 + a^2 + 2a^2)

=2×5a^2

=10 a^2

=10 × 4×4=160 cm ^2