Examples with solutions for Perimeter of a Parallelogram: Using variables

Exercise #1

The parallelogram ABCD has a perimeter equal to 80 cm.

Calculate X.

XXX2X2X2XAAABBBCCCDDD

Video Solution

Step-by-Step Solution

Since in a parallelogram each pair of opposite sides are equal and parallel:

BC=AD=2x BC=AD=2x

AB=CD=x AB=CD=x

Now let's substitute the known data into the formula for calculating the perimeter:

80=2x×2+2×x 80=2x\times2+2\times x

80=4x+2x 80=4x+2x

80=6x 80=6x

Let's divide both terms by 6:

806=6x6 \frac{80}{6}=\frac{6x}{6}

806=x \frac{80}{6}=x

Let's simplify the fraction by 2

403=x \frac{40}{3}=x

Answer

x=403 x=\frac{40}{3}

Exercise #2

Calculate the perimeter of the parallelogram ABCD.

AB is parallel to CD.

XXX101010AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To find the perimeter of the parallelogram ABCD, we will use the formula for the perimeter of a parallelogram:

  • The formula for the perimeter P P is P=2×(length of one base+length of one side) P = 2 \times (\text{length of one base} + \text{length of one side}) .

Given that:

  • The length of the base (either AB or CD) is X X .
  • The length of the side (either AD or BC) is 10.

Substituting these values into the formula for the perimeter, we get:

P=2×(X+10) P = 2 \times (X + 10)

Distribute the 2:

P=2X+20 P = 2X + 20

Therefore, the perimeter of parallelogram ABCD is 2X+20 2X + 20 .

The correct answer, as per the choices given, is choice 4: 2x+20 2x+20 .

Answer

2x+20 2x+20

Exercise #3

Given a parallelogram in which the length of one side is greater than 2 of the length of another side and given that the length of the longest side is X:

AAABBBDDDCCC

Express by X the perimeter of the parallelogram.

Video Solution

Step-by-Step Solution

To solve this problem, we need to calculate the perimeter of the parallelogram using given information. Here are the steps to find the solution:

  • Step 1: Identify the Longest Side.
    The longest side of the parallelogram, denoted by X X , is given as a a . Therefore, a=X a = X .
  • Step 2: Determine the Other Side Length.
    Given a>2b a > 2b , typically X=2b X = 2b as a common interpretation for solving problems.
    Thus, the other side b b is half the longer side: b=X2 b = \frac{X}{2} .
  • Step 3: Apply the Perimeter Formula.
    The perimeter P P of a parallelogram is calculated as P=2(a+b) P = 2(a + b) .
    Plug in the values: a=X a = X , b=X2 b = \frac{X}{2} .
    Thus, perimeter P=2(X+X2)=2(2X2+X2)=2(3X2)=3X P = 2\left(X + \frac{X}{2}\right) = 2\left(\frac{2X}{2} + \frac{X}{2}\right) = 2\left(\frac{3X}{2}\right) = 3X .

Therefore, the perimeter of the parallelogram in terms of X X is 3X \mathbf{3X} .

Answer

3X

Exercise #4

The longest sides of a parallelogram are X cm long and are four times longer than the shorter sides.

AAABBBDDDCCC

Express the perimeter of the parallelogram in terms of X.

Video Solution

Step-by-Step Solution

In a parallelogram, each pair of opposite sides are equal and parallel: AB = CD and AC = BD.

Given that the length of one side is 4 times greater than the other side equal to X, we know that:

AB=CD=4AC=4BD AB=CD=4AC=4BD

Now we replace the data in this equation with out own (assuming that AB = CD = X):

x=x=4AC=4BD x=x=4AC=4BD

We divide by 4:

x4=x4=AC=BD \frac{x}{4}=\frac{x}{4}=AC=BD

Now we calculate the perimeter of the parallelogram and express both AC and BD using X:

P=x+x4+x+x4 P=x+\frac{x}{4}+x+\frac{x}{4}

P=2x+x4+x4=212x P=2x+\frac{x}{4}+\frac{x}{4}=2\frac{1}{2}x

Answer

2.5X cm

Exercise #5

Given a parallelogram in which the length of one side is 2 times the length of the other side and given that the length of the larger side is 0.5X:

AAABBBDDDCCC

Express by X the perimeter of the parallelogram.

Video Solution

Step-by-Step Solution

To solve the problem, follow these steps:

  • Step 1: Identify the given side lengths.
    The longer side of the parallelogram is given as 0.5X0.5X. The other side, being half the length of the long side, is 0.25X0.25X.
  • Step 2: Use the perimeter formula.
    The formula for the perimeter PP of a parallelogram is P=2a+2bP = 2a + 2b, where aa and bb are the lengths of the sides.
  • Step 3: Plug in the side lengths into the formula.
    Substitute a=0.5Xa = 0.5X and b=0.25Xb = 0.25X into the perimeter formula:
    P=2(0.5X)+2(0.25X)=X+0.5X=1.5XP = 2(0.5X) + 2(0.25X) = X + 0.5X = 1.5X.

Thus, the perimeter of the parallelogram expressed in terms of XX is 1.5X1.5X.

Therefore, the correct answer is choice 22, which is 1.5X1.5X.

Answer

1.5X

Exercise #6

Given a parallelogram where the length of one side is greater by 4 than the length of another side and given that the length of the smaller side is X:

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Express by X the perimeter of the parallelogram.

Video Solution

Step-by-Step Solution

To solve the problem, we'll apply the perimeter formula for a parallelogram. We are given that one side a=X a = X and the other side b=X+4 b = X + 4 . The perimeter P P of a parallelogram is calculated by the formula:

P=2(a+b) P = 2(a + b)

Substitute the values of a a and b b :
a=X a = X
b=X+4 b = X + 4

Plug these into the formula:

P=2(X+(X+4)) P = 2(X + (X + 4))

Simplify the expression inside the parentheses:

P=2(2X+4) P = 2(2X + 4)

Distribute the 2:

P=4X+8 P = 4X + 8

Therefore, the perimeter of the parallelogram in terms of X X is 4X+8 4X + 8 .

Answer

4X+8

Exercise #7

A parallelogram has one side that is 2 times longer than the other. The length of the smaller side is X.

AAABBBDDDCCC

Express the circumference of the parallelogram in terms of X.

Video Solution

Step-by-Step Solution

As is true of a parallelogram each pair of opposite sides are equal to one another

AB=CD,AC=BD AB=CD,AC=BD

Given that AB > AC

Let's call AC by the name X and therefore:

AB=2AC=2×x=2x AB=2AC=2\times x=2x

Now we know that:

AB=CD=2x,AC=BD=x AB=CD=2x,AC=BD=x

The perimeter is equal to the sum of all the sides together:

2x+x+2x+x=6x 2x+x+2x+x=6x

Answer

4X+4

Exercise #8

Look at the parallelogram shown below.

AB = 6

AC = X

The perimeter of the parallelogram is 20.

AAABBBDDDCCC6X

Find X.

Video Solution

Step-by-Step Solution

As is true for a parallelogram each pair of opposite sides are equal:

AB=CD=6,AC=BD=x AB=CD=6,AC=BD=x

Calculate X according to the given perimeter:

20=6+6+x+x 20=6+6+x+x

20=12+2x 20=12+2x

2012=2x 20-12=2x

8=2x 8=2x

x=4 x=4

Answer

4

Exercise #9

A parallelogram is shown below.

AB = 8

AC = X+2

The perimeter of the parallelogram is 30.

AAABBBDDDCCC8X+2

Calculate X.

Video Solution

Step-by-Step Solution

The problem involves finding the value of X X in a parallelogram with sides given and a specified perimeter. We will use the formula for the perimeter of a parallelogram.

The formula for the perimeter P P of a parallelogram is:

P=2(a+b) P = 2(a + b)

Given that:

  • One side AB=a=8 AB = a = 8 .
  • The other side AC=b=X+2 AC = b = X + 2 .
  • The perimeter P=30 P = 30 .

Substitute the given values into the perimeter formula:

2(8+(X+2))=30 2(8 + (X + 2)) = 30

Simplify the expression inside the parentheses:

8+X+2=X+10 8 + X + 2 = X + 10

Now the equation becomes:

2(X+10)=30 2(X + 10) = 30

Divide both sides by 2:

X+10=15 X + 10 = 15

Subtract 10 from both sides to solve for X X :

X=1510 X = 15 - 10

Thus:

X=5 X = 5

The value of X X is therefore 5\textbf{5}.

Answer

5

Exercise #10

Below is a parallelogram.

AB = 4

AC = X-2

The perimeter of the parallelogram is 10.

AAABBBDDDCCC4X-2

Calculate X.

Video Solution

Step-by-Step Solution

The problem involves calculating X X for a parallelogram with given side lengths and perimeter. Let's proceed step-by-step:

Step 1: First, recognize that in a parallelogram, opposite sides are equal:
- AB=CD=4 AB = CD = 4 (given)
- AC=BD=X2 AC = BD = X-2

Step 2: Use the perimeter formula for the parallelogram:
P=2(a+b) P = 2(a + b)
where a=AB=4 a = AB = 4 and b=AC=X2 b = AC = X-2 .

Step 3: Plug the perimeter value and side lengths into the formula:
10=2(4+(X2)) 10 = 2(4 + (X - 2))

Step 4: Simplify and solve for X X :
10=2(4+X2) 10 = 2(4 + X - 2)
10=2(X+2) 10 = 2(X + 2)

Step 5: Divide both sides by 2 to eliminate the factor:
5=X+2 5 = X + 2

Step 6: Subtract 2 from both sides to isolate X X :
X=3 X = 3

Therefore, the correct value of X X is 3 3 .

The corresponding choice is option 4.

Answer

3

Exercise #11

Look at the parallelogram below.

AB = 10

AC = X

The perimeter of the parallelogram is 30.

AAABBBDDDCCC10X

Calculate X.

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given information: AB=10 AB = 10 , AC=X AC = X , and the perimeter is 30.
  • Step 2: Apply the formula for the perimeter of a parallelogram: 2(a+b)=perimeter 2(a + b) = \text{perimeter} .
  • Step 3: Substitute the values and solve for X X .

Now, let's work through each step:
Step 1: The problem provides us AB=10 AB = 10 , AC=X AC = X , and the perimeter as 30.
Step 2: The perimeter P P of a parallelogram with sides AB AB and AC AC is given by P=2(AB+AC) P = 2(AB + AC) .
Substitute the known values: 2(10+X)=30 2(10 + X) = 30 .
Step 3: Simplify this equation: 2(10+X)=30 2(10 + X) = 30 Divide both sides by 2: 10+X=15 10 + X = 15 Subtract 10 from both sides to solve for X X : X=5 X = 5

Therefore, the solution to the problem is X=5 X = 5 .

Answer

5

Exercise #12

A parallelogram is shown below.

AB = 5

AC = 2X

The perimeter of the parallelogram is 20.

AAABBBDDDCCC52X

Calculate the length of side AC.

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Use the formula for the perimeter of a parallelogram.
  • Step 2: Set up the equation using the given information.
  • Step 3: Solve for XX and find the length of AC.

Now, let's work through each step:
Step 1: Recall that the perimeter of a parallelogram is given by the formula P=2(a+b)P = 2(a + b), where aa and bb are the lengths of adjacent sides.
Step 2: In our parallelogram, opposite sides are equal. Therefore, the perimeter formula can be expressed as: P=2(AB+AC)=20 P = 2(AB + AC) = 20 Substituting the given lengths: 2(5+2X)=20 2(5 + 2X) = 20
Step 3: Simplify the equation: 2×(5+2X)=2010+4X=204X=10X=2.5 2 \times (5 + 2X) = 20 \\ 10 + 4X = 20 \\ 4X = 10 \\ X = 2.5 Now, substitute back to find the length of side AC: AC=2X=2×2.5=5 AC = 2X = 2 \times 2.5 = 5

Therefore, the length of side AC is 5\bold{5}.

The correct choice from the given options is 3\bold{3}: 5\bold{5}.

Answer

5

Exercise #13

Shown below is a parallelogram.

AB = 7

AC = 0.5X

The perimeter of the parallelogram is 21.

AAABBBDDDCCC70.5X

Calculate side AC.

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the formula for the perimeter of a parallelogram.
  • Step 2: Substitute the given values into the perimeter formula.
  • Step 3: Solve for the unknown variable X X .
  • Step 4: Determine the specific length of AC using the value of X X .

Now, let's work through each step:

Step 1: The formula for the perimeter of a parallelogram is given by

P=2(a+b) P = 2(a + b)

where a a and b b are the lengths of the two pairs of sides.

Step 2: Substitute the known values into the formula. Here, let a=AB=7 a = AB = 7 and b=AC=0.5X b = AC = 0.5X .

Perimeter =21 = 21 , so:

21=2(7+0.5X) 21 = 2(7 + 0.5X)

Step 3: Solve for the unknown variable X X .

First, divide both sides of the equation by 2 to isolate the terms inside the parenthesis:

10.5=7+0.5X 10.5 = 7 + 0.5X

Subtract 7 from both sides:

3.5=0.5X 3.5 = 0.5X

Multiply both sides by 2 to isolate X X :

X=7 X = 7

Step 4: Determine the length of AC:

Substitute back to find 0.5X=AC 0.5X = AC :

AC=0.5×7=3.5 AC = 0.5 \times 7 = 3.5

Therefore, the length of side AC is 3.5 3.5 .

Answer

3.5

Exercise #14

How long is side BC given that the perimeter of the parallelogram is 30 cm?

CD=2x CD=2x

2x2x2xAAABBBCCCDDD

Video Solution

Step-by-Step Solution

To solve this problem, we begin by using the formula for the perimeter of a parallelogram:

The perimeter P P is given by: P=2(a+b) P = 2(a + b)

Given: P=30 cm P = 30 \text{ cm} , and CD=2x CD = 2x . We know AB=2x AB = 2x since opposite sides of a parallelogram are equal. So, we write:

  • P=2(BC+CD)=30 P = 2(BC + CD) = 30
  • 2(BC+2x)=30 2(BC + 2x) = 30
  • BC+2x=15 BC + 2x = 15 (after dividing both sides by 2)
  • BC=152x BC = 15 - 2x

Thus, the length of side BC BC is given by:

BC=152x BC = 15 - 2x

Therefore, the correct option is:

  • Choice 1: 152x 15 - 2x

This matches the problem's given correct answer.

Answer

152x 15-2x

Exercise #15

ABCD is a parallelogram whose perimeter is equal to 22 cm.

Side AB is smaller by 5 than side AD

The height of the parallelogram for the side AD is 2 cm

What is the area of the parallelogram?

AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To solve this problem, we will follow these steps:

  • Step 1: Setup and solve the equations for side lengths ABAB and ADAD.
  • Step 2: Calculate the area using the base ADAD and the given height of 2 cm.

Let's begin:

Step 1: Calculate side lengths

Given that the perimeter is 22 cm, we have:

\begin{equation} 2(AB + AD) = 22 \end{equation}

The equation simplifies to:

\begin{equation} AB + AD = 11 \end{equation}

We are also given:

\begin{equation} AB = AD - 5 \end{equation}

Substitute this in the first equation:

\begin{equation} (AD - 5) + AD = 11 \end{equation} \begin{equation} 2AD - 5 = 11 \end{equation} \begin{equation} 2AD = 16 \end{equation} \begin{equation} AD = 8 \end{equation}

Now, substitute AD=8AD = 8 back into the expression for ABAB:

\begin{equation} AB = 8 - 5 = 3 \end{equation}

Step 2: Calculate the area

With AD=8AD = 8 cm as the base (since the problem specifies height to ADAD) and the given height of 2 cm, the area is calculated as:

\begin{equation} A = \text{base} \times \text{height} = 8 \times 2 = 16 \, \text{cm}^2 \end{equation}

Therefore, the area of the parallelogram is 16 cm².

Answer

16 cm²

Exercise #16

ABCD is a parallelogram whose perimeter is equal to 24 cm.

The side of the parallelogram is two times greater than the adjacent side (AB>AD).

CE is the height of the side AB

The area of the parallelogram is 24 cm².

Find the height of CE

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Video Solution

Step-by-Step Solution

The perimeter of the parallelogram is calculated as follows:

SABCD=AB+BC+CD+DA S_{ABCD}=AB+BC+CD+DA Since ABCD is a parallelogram, each pair of opposite sides is equal, and therefore, AB=DC and AD=BC

According to the figure that the side of the parallelogram is 2 times larger than the side adjacent to it, it can be argued thatAB=DC=2BC AB=DC=2BC

We inut the data we know in the formula to calculate the perimeter:

PABCD=2BC+BC+2BC+BC P_{ABCD}=2BC+BC+2BC+BC

We replace the given perimeter in the formula and add up all the BC coefficients accordingly:

24=6BC 24=6BC

We divide the two sections by 6

24:6=6BC:6 24:6=6BC:6

BC=4 BC=4

We know thatAB=DC=2BC AB=DC=2BC We replace the data we obtained (BC=4)

AB=DC=2×4=8 AB=DC=2\times4=8

As ABCD is a parallelogram, then all pairs of opposite sides are equal, therefore BC=AD=4

To find EC we use the formula:AABCD=AB×EC A_{ABCD}=AB\times EC

We replace the existing data:

24=8×EC 24=8\times EC

We divide the two sections by 824:8=8EC:8 24:8=8EC:8

3=EC 3=EC

Answer

3 cm

Exercise #17

ABCD is a parallelogram whose perimeter is equal to 22 cm.

AC=4 height of the parallelogram for side CD is 3 cm

Calculate the area of the parallelogram

444AAABBBDDDCCC

Video Solution

Answer

21 cm².

Exercise #18

Given a parallelogram in which the length of one side is 2 greater than the length of another side and given that the length of the larger side is 2X:

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Express by X the perimeter of the parallelogram.

Video Solution

Answer

6X