Examples with solutions for Surface Area of a Cuboid: Express using

Exercise #1

Express the surface area of the rectangular prism in terms of X using the given data.

333555XXX

Video Solution

Step-by-Step Solution

To find the surface area of the rectangular prism in terms of X X , follow these steps:

  • Step 1: Identify the dimensions:
    • Length l=X l = X
    • Width w=5 w = 5
    • Height h=3 h = 3
  • Step 2: Use the surface area formula for a rectangular prism: S=2(lw+lh+wh) S = 2(lw + lh + wh)
  • Step 3: Substitute the given values: S=2(X5+X3+53) S = 2(X \cdot 5 + X \cdot 3 + 5 \cdot 3)
  • Step 4: Simplify the expression: S=2(5X+3X+15) S = 2(5X + 3X + 15) S=2(8X+15) S = 2(8X + 15) S=16X+30 S = 16X + 30
  • Step 5: Therefore, the surface area of the rectangular prism expressed in terms of X X is 16X+30 16X + 30 .

This matches with choice 1.

Thus, the solution to the problem is 16X+30 16X + 30 .

Answer

16X+30

Exercise #2

Express the surface area of the rectangular prism below in terms of a, b, and c.

cccaaabbb

Video Solution

Step-by-Step Solution

The problem requires us to find the surface area of a rectangular prism in terms of aa, bb, and cc. To find this, we use the standard formula for the surface area of a cuboid.

The surface area of a cuboid is given by:

S=2(ab+bc+ca) S = 2(ab + bc + ca)

Explanation of the formula:

  • Each face of the cuboid is a rectangle. There are three unique rectangles in a cuboid:
  • Two faces with dimensions a×ba \times b,
  • Two faces with dimensions b×cb \times c,
  • Two faces with dimensions c×ac \times a.

These three pairs of faces contribute to the total surface area as follows:

  • Area of the two a×ba \times b faces: 2×(ab)2 \times (ab)
  • Area of the two b×cb \times c faces: 2×(bc)2 \times (bc)
  • Area of the two c×ac \times a faces: 2×(ca)2 \times (ca)

Adding these areas together gives us the total surface area:

S=2ab+2bc+2ca S = 2ab + 2bc + 2ca

This simplifies to 2(ab+bc+ca)2(ab + bc + ca).

Given the choices, the correct expression for the surface area is 2ac+2ab+2bc2ac + 2ab + 2bc.

Answer

2ac+2ab+2bc 2ac+2ab+2bc

Exercise #3

Express the surface area of the cube in terms of a.

aaa

Video Solution

Step-by-Step Solution

To solve this problem, we'll recall the following relevant formula:

  • The surface area of a cube is given by the formula: Surface Area=6a2 \text{Surface Area} = 6a^2 .

Let's break down the solution in steps:

Step 1: Identify the characteristic of the cube.
A cube is a three-dimensional shape with six identical square faces.

Step 2: Determine the area of one face.
Each face of the cube is a square with side length a a , so the area of one face is a2 a^2 .

Step 3: Calculate the total surface area.
Since a cube has six identical faces, the total surface area is six times the area of one face:

Surface Area=6×a2=6a2 \text{Surface Area} = 6 \times a^2 = 6a^2

Therefore, the surface area of the cube in terms of a a is 6a2 6a^2 .

Answer

6a2 6a^2

Exercise #4

Express the surface area of the rectangular prism below in terms of a.

111555aaa

Video Solution

Step-by-Step Solution

To solve this problem, we must find the surface area of the rectangular prism with given dimensions 1 1 , 5 5 , and a a .

The formula for the surface area S S of a rectangular prism with length l l , width w w , and height h h is:

S=2(lw+lh+wh) S = 2(lw + lh + wh)

For this prism, let's identify the dimensions:

  • Length (l l ) = 1
  • Width (w w ) = 5
  • Height (h h ) = a

Now, substitute these dimensions into the surface area formula:

S=2(1×5+1×a+5×a) S = 2(1 \times 5 + 1 \times a + 5 \times a)

Simplify the expression inside the parentheses:

S=2(5+a+5a) S = 2(5 + a + 5a)

Combine the terms:

S=2(5+6a) S = 2(5 + 6a)

Multiply through by 2:

S=10+12a S = 10 + 12a

Thus, the surface area of the rectangular prism expressed in terms of a a is 12a+10 12a + 10 .

Answer

12a+10 12a+10

Exercise #5

Express the surface area of the cuboid below in terms of a.

a

Video Solution

Step-by-Step Solution

To find the surface area of a cuboid, I need to identify its three dimensions from the diagram and apply the surface area formula.

From the SVG diagram labels, the three dimensions of the cuboid are:

  • Length: a2a^2
  • Width: a+2a + 2
  • Height: aa

The surface area formula for a cuboid with dimensions ll, ww, and hh is:
SA=2(lw+lh+wh)SA = 2(lw + lh + wh)

Let me calculate each face area:

  • Face 1 (length × width): a2(a+2)=a3+2a2a^2 \cdot (a+2) = a^3 + 2a^2
  • Face 2 (length × height): a2a=a3a^2 \cdot a = a^3
  • Face 3 (width × height): (a+2)a=a2+2a(a+2) \cdot a = a^2 + 2a

Now, applying the surface area formula:
SA=2[(a3+2a2)+a3+(a2+2a)]SA = 2[(a^3 + 2a^2) + a^3 + (a^2 + 2a)]
SA=2[2a3+3a2+2a]SA = 2[2a^3 + 3a^2 + 2a]
SA=4a3+6a2+4aSA = 4a^3 + 6a^2 + 4a

Therefore, the surface area of the cuboid expressed in terms of aa is 4a3+6a2+4a4a^3 + 6a^2 + 4a.

Answer

4a3+6a2+4a 4a^3+6a^2+4a

Exercise #6

Look at the cuboid below:

cccaaabbb

Choose the correct representation of its surface area.

Video Solution

Step-by-Step Solution

To find the surface area of a cuboid, we consider its six rectangular faces. A cuboid has three pairs of opposite faces. Each pair of faces shares the same area.

The surface area S S of a cuboid with dimensions a a , b b , and c c is calculated by finding the area of each of these rectangular faces and then summing them up. Specifically, we consider:

  • The area of the first pair of opposite faces with dimensions a a and b b is ab ab .
  • The area of the second pair of faces with dimensions b b and c c is bc bc .
  • The area of the third pair of faces with dimensions a a and c c is ac ac .

The total surface area is thus given by the formula:

S=2(ab+bc+ac) S = 2(ab + bc + ac)

By analyzing the provided choices, it's clear that the correct formula for the surface area of the cuboid is 2(a×b+b×c+a×c) 2(a\times b + b\times c + a\times c) .

Therefore, the solution to the problem is 2(a×b+b×c+a×c) 2(a \times b + b \times c + a \times c) .

Answer

2(a×b+b×c+a×c) 2(a\times b+b\times c+a\times c)