Question

Help will mark brainlist if it correct If each edge of a cube is increased by 2 inches, the

Answer 1

Answer:

D. sum of these edges is increased by 24 inches -- True

Step-by-step explanation:

Given a cube and its edge is increased by 2 inches.

To study the effect of this increase in the Volume, area of each face, diagonal and sum of edges.

Solution:

Let the side of original cube = a inches.

Formula for volume of cube:

$V =side^3 = a^3$

If the side is increased by 2 inches, the side becomes (a+2) inches.

So, new volume, $V' = (a+2)^3$

Using the formula:

$(x+y)^3 =x^3+y^3+3xy(x+y)$

$V' = (a+2)^3 = a^3+8+3\times 2 \times a(a+2)=a^3+8+6a(a+2)$

So, $V' = V + 8+6a(a+2)$

Volume increased by 8+6a(a+2) [which is not equal to 8]

So, statement is false:

A. volume is increased by 8 cubic inches  -- False

Each face in a cube is a square.

Area of each face, A = $side^2 = a^2$

New area, A' = $(a+2)^2$

Using the formula: $(x+y)^2 =x^2+y^2+2xy$

$A' = a^2+4+4a$

Area increased by 4+4a [which is not equal to 4 sq inches]

B. area of each face is increased by 4 square inches -- False

Diagonal of each face = $a\sqrt2$

Increase of 2 in the edge:

New diagonal = $(a+2)\sqrt2 = a\sqrt2+2\sqrt2$

So, increase of $2\sqrt2$ not 2.

C. diagonals of each face is increased by 2 inches -- False

There are 12 number of edges in a square.

So sum of all 12 edges  = 12a

When edge is increased by 2, sum of all edges = 12(a+2) = 12a + 24

An increase of 24.

D. sum of these edges is increased by 24 inches -- True