Formula for Calculating the Perimeter of a Rectangle

Buzz

Content

How to calculate the perimeter of a rectangle, various problem types, and illustrated examples.

I. Formula for Calculating the Perimeter of a Rectangle

II. Illustrated Examples of Calculating the Perimeter of a Rectangle

1. Exercise: Calculate the perimeter of a rectangle given the width and length

2. Exercise: Calculate the perimeter of a rectangle given the ratio and difference between length and width

3. Calculate the Perimeter of a Rectangle with Known Area, Length, or Width

Reinforce your understanding of the formula for calculating the perimeter of a rectangle in grades 3 and 4. Additionally, refer to examples and exercises to master various problem types and solve exercises efficiently.

A rectangle is a special quadrilateral with equal and 90-degree angles, parallel and equal opposite sides. This makes calculating the perimeter of a rectangle easy to learn and remember. If you've forgotten the formula for calculating the perimeter of a rectangle, check out the article below.

How to calculate the perimeter of a rectangle, various problem types, and illustrated examples.

Article Table of Contents:
I. Formula for Calculating the Perimeter of a Rectangle.
II. Illustrated Examples of Calculating the Perimeter of a Rectangle.
  1. Calculate the perimeter of a rectangle when width and length are known.
  2. Calculate the perimeter of a rectangle when the ratio and difference between length and width are known.
  3. Calculate the perimeter of a rectangle when the area is known.

I. Formula for Calculating the Perimeter of a Rectangle

Consider the rectangle ABCD below with length a and width b

We will have the formula for the perimeter of a rectangle as follows

Introduction:

+ P represents the perimeter of a rectangle
+ AB, BC are the adjacent sides of the rectangle.

II. Illustrated Examples of Calculating the Perimeter of a Rectangle

Below are exercises applying knowledge of rectangle perimeter from basic to advanced. Although there are numerous examples, this article will present the most typical ones to help students approach various exercise types.

1. Exercise: Calculate the perimeter of a rectangle given the width and length

Example 1: Find the perimeter of rectangle ABCD when a = 20cm and b = 15cm

- Solution: Applying the formula for rectangle perimeter mentioned above, we get

So, the perimeter of rectangle ABCD will be: 70cm

Similarly, students can apply the above formula to solve an example of calculating the perimeter of a rectangle with a length of 25 cm and a width of 15 cm (answer: 80 cm)

2. Exercise: Calculate the perimeter of a rectangle given the ratio and difference between length and width

Solution Method: Solving problems using the difference-ratio method:

- Summarize the problem with a line segment diagram (segments that need to be equal)
- Find the difference of the segments according to the diagram
- Find the smaller number (width) by dividing the difference by the equal segment difference, then multiply by the segment number of the smaller number
- Find the larger number (length) by multiplying the width by 2 (because the length is twice the width)

* Apply the formula for calculating the perimeter of a rectangle: P = (a + b) x 2.

Example 2: Calculate the perimeter of a rectangle given that the length is twice the width and exceeds the width by 15m;

We have the diagram:

According to the diagram, the difference in equal segments is:
2 - 1 = 1 (segment)

Width of the land plot is
15 : 1 x 1 = 15 (m)

Length of the land plot is:
15 x 2 = 30 (m)

Perimeter of the land plot is:
(30 + 15) x 2 = 90 (m)

Answer: 90 m.
Answer: Width: 15m, length: 30m, perimeter: 90 (m)

Example 3: Calculate the perimeter of a rectangle knowing that the length is 3/2 times the width and exceeds the width by 10m

Answer: The length of the rectangle is 30m, the width is 20m, and the perimeter of the rectangle is 100

3. Calculate the Perimeter of a Rectangle with Known Area, Length, or Width

Solution Method:

To solve exercises of this type, students need to apply the formula for the area of a rectangle S(ABCD)= 2.a.b and the perimeter of a rectangle P = 2.(a+b)

Example 4: Calculate the perimeter of a rectangle with an area of 36 square cm and a width of 6cm

Answer: The perimeter of the rectangle is 24cm

Above are the formulas for calculating the perimeter of a rectangle and illustrated examples. Hopefully, with this article, you will find it easy to apply the formulas and calculate the perimeter of a rectangle to solve the problems you encounter.

A parallelogram is also a special quadrilateral; we can consider a rectangle as a special parallelogram. Therefore, the formula for calculating the perimeter of a parallelogram is similar to calculating the perimeter of a rectangle.

The content is developed by the Mytour team with the aim of customer care and solely to inspire travel experiences. We do not take responsibility for or provide advice for other purposes.

If you find this article inappropriate or containing errors, please contact us via email at [email protected]

Frequently Asked Questions

What is the formula for calculating the perimeter of a rectangle?

The formula for calculating the perimeter of a rectangle is P = 2(a + b), where 'a' is the length and 'b' is the width. This formula is straightforward and easy to remember, making it accessible for students in grades 3 and 4.

How can I calculate the perimeter of a rectangle when I know the length and width?

To calculate the perimeter of a rectangle when the length and width are known, simply use the formula P = 2(a + b). For example, if the length is 20 cm and the width is 15 cm, the perimeter would be 70 cm.

Can I find the perimeter of a rectangle if I only have the area?

Yes, it is possible to find the perimeter of a rectangle if the area and one dimension are known. You would use the area formula S = a * b and the perimeter formula P = 2(a + b) to calculate the unknown side.

What steps are involved in calculating the perimeter from the length-to-width ratio?

To calculate the perimeter from the length-to-width ratio, first determine the actual dimensions using the given ratio and any known difference. Then, apply the perimeter formula P = 2(a + b) to find the perimeter.

What should I do if I forget the perimeter formula for a rectangle?

If you forget the perimeter formula for a rectangle, remember that it is P = 2(a + b). Reviewing the properties of rectangles can help reinforce your understanding and memory of this important geometric concept.