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Perimeter Of A Parallelogram Explained Clearly

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What Is The Formula For The Perimeter Of A Parallelogram With Examples

Perimeter of a Parallelogram, This article will include all the things basic to the problem practice all the things we shall be covering. We shall try to find the answers of some questions like what is perimeter , what do you understand by parallelogram , what are the ways to determine perimeter of parallelogram , then we shall cover the problems along with the solutions and then we shall discuss some Frequently asked questions (FAQs).


In Geometry, the word Perimeter is used as the indicator of the path or length. The word Perimeter originated from two Greek words "PERI" (which means around) and "METER"(which means measure) means measurement of all around the path. 


A perimeter is a length which encompasses/surrounds a two-dimensional or planner shape. The term can be used either for the path, or its length—in a single dimension system. It can be visualized as the length of the boundary of a shape. The perimeter of a circle or ellipse is usually called its circumference.


Let's Recall the Parallelogram !!

In Euclidean geometry, a parallelogram is like a simple quadrilateral which contains two pairs of Parallel sides. The opposite facing sides or Parallel pair sides of a parallelogram are of equal length and the opposite facing angles (as angle BAC = angle BCD in below figure) of a parallelogram are of equal measure.


Example :

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Properties of Parallelogram

  • Opposite facing parallel sides are congruent (AB = DC).

  • Opposite facing angles are Equal (D = B).

  • Consecutive Two angles are supplementary (i.e. A + D = 180°).

  • If one angle is right, then all angles will be right.

  • The diagonals of a parallelogram will be bisected to each other.

  • Both the diagonals of a parallelogram separate it into two congruent triangles.

Perimeter of Parallelogram

A Perimeter of any figure can be defined in various mentioned ways.

  1. A Perimeter of any polygon is the total length along the outside of the same polygon. 

  2. A Perimeter of any figure is the total length of all its sides.

  3. A Perimeter is the length of the boundary or length of line of separation of shape with the surrounding.

  4. A Perimeter is the measurement of the length of the outline of a shape.

Determining the Perimeter has many practical applications. For example, it could be used to find out the number of revolutions of a wheel, length of a fence surrounding a yard or garden, the amount of wool wound around a spool will also be related to the perimeter of the spool, the distance ran by a runner around a path, etc.

Let “a” and “b” are the sides of a parallelogram. then, the perimeter of a parallelogram formula will be as follows:

We already know that the opposite face sides of a parallelogram are parallel and also equal to each other. Thus, the formula for determining the perimeter of a parallelogram will be given by:

So, the perimeter of Parallelogram, P = a + b + a + b units

P = 2a +2b

P = 2(a+b)

Therefore, the perimeter of a parallelogram, P will be 2(a+b) units


Perimeter of a Parallelogram with Base(b) and Height(h)

Let us assume a parallelogram with base and height is given. If “b” is the base length of the parallelogram and “h” is the height length of the parallelogram, then the formula will be derived as follows:

According to the properties of the parallelogram, the opposite face sides are parallel and also equal to each other, so the parallelogram perimeter will be determined as two times of sum of the base and height.

 [Image will be Uploaded Soon]

Thus, the formula for the perimeter of a parallelogram will be given by:

P = 2 (b +h/cos θ)

where θ is the mentioned angle BAE, which is formed between the height and side of the parallelogram, i.e. AE and AB.


Problems with Solutions

Example 1:

Determine the perimeter of a parallelogram with the base and side lengths of 10cm and 5cm, respectively.

 

Solution:

Given:

Base length of a parallelogram = 10 cm

Side length of a parallelogram = 5 cm

We already  know that the perimeter of a parallelogram is given by, P = 2(a+b) units.

Substitute the values

P = 2(10+5)

P = 2(15)

P = 30 cm

Therefore, the perimeter of a parallelogram will be 30 cm.

 

Example 2:

Determine the length of another side of the parallelogram whose base is 5 cm and the perimeter is 40 cm.

 

Solution:

Given:

Base, h = 5cm

Perimeter, p = 40cm

We already  know that the perimeter of a parallelogram is given by, P = 2(a+b) units.

Now substitute the given values in the formula,

40 = 2 (a +5)

40 = 2a + 10

2a = 40-10

2a = 30

a = 30/2

a = 15 cm

Thus, the length of the other side of the parallelogram will be 15 cm.

FAQs on Perimeter Of A Parallelogram Explained Clearly

1. What is the perimeter of a parallelogram?

The perimeter of a parallelogram is the total distance around it, calculated by adding all four sides. Since opposite sides of a parallelogram are equal, the perimeter formula is:

P = 2(a + b)

Where:

  • a = length of one side
  • b = length of the adjacent side
This formula works because a parallelogram has two pairs of equal opposite sides.

2. What is the formula for the perimeter of a parallelogram?

The formula for the perimeter of a parallelogram is P = 2(a + b). Here:

  • a = one side length
  • b = adjacent side length
You add the two different side lengths and multiply the sum by 2 because opposite sides are equal in a parallelogram.

3. How do you find the perimeter of a parallelogram step by step?

To find the perimeter of a parallelogram, use the formula P = 2(a + b).

Follow these steps:

  • Step 1: Identify the lengths of two adjacent sides (a and b).
  • Step 2: Add them: a + b.
  • Step 3: Multiply the result by 2.
Example: If a = 6 cm and b = 4 cm,
P = 2(6 + 4) = 2 × 10 = 20 cm.

4. How is the perimeter of a parallelogram different from its area?

The perimeter of a parallelogram measures the total boundary length, while the area measures the space inside it.

  • Perimeter formula: P = 2(a + b)
  • Area formula: A = base × height
Perimeter is measured in linear units (cm, m), whereas area is measured in square units (cm², m²).

5. Can you find the perimeter of a parallelogram if only one side is given?

No, you cannot find the perimeter of a parallelogram with only one side unless additional information is given. The formula P = 2(a + b) requires two adjacent side lengths. Without both side measurements or another relation, the perimeter cannot be determined.

6. What is the perimeter of a parallelogram with sides 8 cm and 5 cm?

The perimeter of a parallelogram with sides 8 cm and 5 cm is 26 cm.

Using the formula:
P = 2(a + b)
P = 2(8 + 5)
P = 2 × 13 = 26 cm

7. Does the height affect the perimeter of a parallelogram?

No, the height does not affect the perimeter of a parallelogram. The perimeter depends only on the side lengths using P = 2(a + b). Height is used to calculate the area (A = base × height), not the perimeter.

8. Are all sides equal in a parallelogram when calculating perimeter?

No, only opposite sides are equal in a parallelogram. When calculating the perimeter, remember:

  • Two sides have length a
  • The other two sides have length b
This is why the formula is P = 2(a + b) and not 4a (unless it is a special case like a rhombus).

9. What is the perimeter of a parallelogram if all sides are equal?

If all sides of a parallelogram are equal, it is a rhombus, and the perimeter is P = 4a. Since all four sides have the same length, you simply multiply one side by 4.

Example: If each side is 7 cm,
P = 4 × 7 = 28 cm.

10. What are common mistakes when finding the perimeter of a parallelogram?

A common mistake is confusing the perimeter formula with the area formula. Remember:

  • Perimeter: P = 2(a + b)
  • Area: A = base × height
Other mistakes include:
  • Using height instead of side length
  • Forgetting to multiply by 2
  • Assuming all sides are equal when they are not
Always identify the two adjacent sides before calculating.