Two cubes, each of volume 64 cm3, are joined end to end. Find the total surface area of the resulting cuboid.


volume of each cube = 64 cm3


Let a be the side length of each cube


a3 = 64


a = 4 cm


The figure shows both the cubes joined together after joining we get a cuboid of length 2a and breadth a and height a


Length of cuboid formed = l = 2a


l = 8 cm


Breadth of cuboid formed = b = 4 cm


Height of cuboid formed = h = 4 cm


In the cuboid so formed there are 4 rectangular surfaces of length l = 8 and breadth b = 4 and 2 square surfaces of length 4


Total surface area of cuboid = 4 × l × b + 2a2


= (4 × 8 × 4) + (2 × 42)


= 128 + 32


= 160 cm2


Total surface area of cuboid = 160 cm2


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