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In elementary school math problems, geometry is divided into various basic shapes such as squares, rectangles, parallelograms, trapezoids, triangles,... Geometry problems will then revolve around the formulas for finding the perimeter, area of these geometric solids.
Theory, formula for finding the perimeter of a rectangle
And if you happen to be asked by children at home to provide a solution to the problem of calculating the perimeter of a rectangle but do not remember how to do it, the article sharing the formula for finding the perimeter of a rectangle below from Mytour.vn will be very helpful to you.
Calculating the perimeter of a rectangle
1. Formula for calculating the perimeter of a rectangle
According to international mathematical conventions, the perimeter of a rectangle is calculated using the following formula:
P = (Length + Width) X 2
Where:
+ A: Length of the rectangle
+ B: Width of the rectangle
+ P: perimeter of a rectangle
With this calculation method, we can also find the formula for half the perimeter of a rectangle:
1/2 P = A + B
2. What is the perimeter of a rectangle?
To obtain the formula as above, we need to understand the nature of the perimeter of a rectangle. Specifically:
- Concept: A rectangle is a quadrilateral with 4 right angles and 2 pairs of equal-length sides
- Theory of calculating the perimeter of a rectangle: The perimeter of a rectangle equals twice the sum of the length and width of that rectangle.
To understand more about the concept, how to calculate the perimeter and area of a rectangle, you can refer to Wiki by clicking on this link.
Theory of calculating the perimeter of a rectangle
3. Some exercises on calculating the perimeter of a rectangle for grade 3
Exercise 1: Given rectangle ABCD where AB = 8cm and BD = 6m. Calculate the perimeter of the rectangle:
Problem 1: For rectangle ABCD where length AB = 8cm and width BD = 6m. Calculate the perimeter of the rectangle:
Solution:
Applying the formula for calculating the perimeter of a rectangle, we have: P (ABCD) = (AB + BD) x 2 = (8 + 6) x 2 = 28cm
So the perimeter of rectangle ABCD is 28 cm
Exercise 2: Calculate the perimeters of the following rectangles:
A. Rectangle 1: Length 10cm, width 5cm
B. Rectangle 2: Length 2dm, width 13cm
Solution:
A. The perimeter of rectangle 1 is: (10+5)x2=30 (cm)
B. The perimeter of rectangle 2 is: ((2 x 10) + 13) x 2 = (66 cm)
Answer: a) 30cm . b)66 cm
Exercise 3: Example of calculating the length of a rectangle
Find the area of a rectangle with a width of 8cm and a perimeter three times the width?
Solution:
According to the data provided in the problem, we have:
The width of the rectangle is 8 cm, or b = 8 cm
The perimeter of the rectangle is three times the width, or P = 3 x a
Based on the formula for calculating the perimeter of a rectangle, we have
P = (a+b) x 2 or 3 x a = (a + 8) x 2
Thus, 3a = 2a + 16 => a = 16 centimeters
Answer: The length of the rectangle is 16 cm
Knowing the formula to calculate the perimeter of a rectangle not only helps reinforce knowledge to guide solving perimeter and area exercises for elementary school students but also teaches how to apply it practically to calculate the perimeter of fields, real estate, or rectangular objects within one's home.
Alongside calculating the perimeters of geometric shapes, a parallelogram is a figure with 2 pairs of parallel and equal sides, and 2 symmetrically equal angles. If you happen to forget or are unsure of the exact formula for finding the perimeter of a parallelogram, this article on how to calculate the perimeter of a parallelogram by Mytour.vn will help address your concern.
https://Mytour.vn/cach-tinh-chu-vi-hinh-chu-nhat-25720n.aspx
