Question

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

A) 216 cms B) 108 cms C) 54 cms D) 162 cms

Answer 1

$\sf\green{GIVEN:}$

S.A of cube=486 cm²

Therefore:

As,S.A of cube= 6×a²

➡ 486 cm² = 6×a²

➡ 486 cm² ÷ 6 = a²

➡ 81 cm² = a²

Therefore,

➡a=√(81cm²)

➡ a= 9 cm

$\tt\red{NOW,}$

Number of edges a cube have= 12 edges

Therefore, Sum of the edges=

➡9+9+9+9+9+9+9+9+9+9+9+9

➡ 108 cm

Hence, Option B is the correct answer.

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