Question 78

Total surface area of a cube is 486 sq cm, find sum of length of all its edges?

Solution

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

Total surface area of cube = $$6a^2 = 486$$

=> $$a^2 = \frac{486}{6} = 81$$

=> $$a = \sqrt{81}=9$$ cm

Number of edges in a cube = 12

$$\therefore$$ Sum of all edges = $$12 \times 9 = 108$$ cm

=> Ans - (B)

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