The volume of a cube is numerically equal to sum of its edges. What is

1.	The volume of a cube is numerically equal to sum of its edges. What is the total surface area in square units ?(a) 12 (b) 36 (c) 72 (d) 144
Answer» (c) 72 Let a be the length of an edge of a cube. Then, a³ = 12a (∵ A cube has 12 edges) ⇒ a² = 12 ⇒ a = 2√3 ∴ Total surface area of cube = 6a² = 6 x (2√3)² = 72.

The volume of a cube is numerically equal to sum of its edges. What is the total surface area in square units ?(a) 12 (b) 36 (c) 72 (d) 144

Answer»

(c) 72

Let a be the length of an edge of a cube. Then,

a³ = 12a (∵ A cube has 12 edges)

⇒ a² = 12 ⇒ a = 2√3

∴ Total surface area of cube = 6a² = 6 x (2√3)² = 72.