Q7 of 56 Page 13

Two cubes each of volume 27 cm3 are joined end to end to form a solid. Find the surface area of the resulting cuboid. (CBSE 2011)

Given: Volume of the cube = 27 cm3


Since volume of cube = (Side)3


∴ (Side)3 = 27cm3


= (3 cm)3


Thus, Side = a = 3 cm


Now, as two cubes are joined from end to end, then


Length of resulting cuboid = l = 2 × 3 = 6 cm


Breadth of resulting cuboid = b = 3 cm


Height of resulting cuboid = h = 3 cm


Surface area of a cuboid = 2 × [lb + bh + hl]


= 2 × [(6 × 3) + (3 × 3) + (3 × 3)]


= 2 × [45]


= 90 cm2

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