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

Options

A. 486 `"सेमी."^(2)`
B. 496 `"सेमी."^(2)`
C. 586 `"सेमी."^(2)`
D. 658 `"सेमी."^(2)`

Answer

A

Explanation

नये घन का आयतन = `6^(3)+8^(3)+1^(3)`
= 216 + 512 + 1 = 729 `cm^(3)`
`therefore` नये घन की भुजा = `root(3)(729)=9cm`
`therefore` नये घन का पृष्ठीय क्षेत्रफल = `6xx9^(2)`
= `6xx81=486cm^(2)`