Question 112

Three cubes of sides 6 cm, 8 cm and 1 cm are melted to form a new cube. The surface area of the new cube is

Solution

Sides of the three cubes = 6, 8 & 1 cm

=> Total volume of the three cubes = $$6^3 + 8^3 + 1^3$$

= 216 + 512 + 1 = 729

Let side of new cube = $$a$$ cm

Acc to ques :

=> $$a^3$$ = 729

=> $$a = \sqrt[3]{729}$$ = 9 cm

=> Surface area of new cube = $$6 a^2$$

= $$6 * 9^2$$ = 486 $$cm^2$$

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