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The quadrilateral is a quite special image in the basic knowledge of geometric mathematics. Because it will have many different types, so the knowledge that children need to grasp will also be more. So, let’s find out what that knowledge is.

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What is the quadrilateral?

For geometry in mathematics, the quadrilateral is the most common image with many different types. Basically, the quadrilateral is a sense of 4 vertices and 4 sides. There will be no 2 sides in the same line.

The quadrilateral may be a double quadrilateral (there are 2 pairs of intersections) or single quadrilateral (no pair of opposite edges). In particular, the single quadrilateral may also be concave or convex.

The quadrilateral is denoted as follows: ABCD The sum of the angle of the quadrilateral is 360 degrees, ie ∠A + ∠b + ∠C + ∠d = 360 ̊

Properties of quadrilateral in geometry

In the quadrilateral, there are two properties:

Properties 1: Cross -shaped properties

In the convex quadrilateral, there will be 2 diagonal intersections at a point in the quadrilateral. Conversely, if the quadrilateral has 2 diagonal lines intersecting at the intersection of its inner domain, it is a convex quadrilateral.

Properties 2: The angular properties of the quadrilateral

The sum of the quadrilateral corners is equal to 360 degrees.

Classification of common quadrilateral shapes

In the quadrilateral will be divided into the following basic categories:

• Single quadrilateral: This is a quadrilateral that has no side to intersect.

• Convex quadrilateral: All the inner corners of the figure are less than 180 °, and the two diagonal lines are grasped the inside of the image. Or understand more simply, this is a quadrilateral that always lies in half of the plane containing any edge.

• Concave quadrilateral: This is a quadrilateral containing an inner angle with a measurement greater than 180 °, along with one of the two diagonal lines outside the quadrilateral.

• Irregular quadrilateral: In the quadrilateral, there is no pair of edges in parallel with each other. This picture is often used to represent the convex quadrilateral.

Special quadrilateral

In addition to the above basic quadrilateral, in the geometry there are some special quadrilateral such as:

• Trapezoid: This is a quadrilateral with at least 2 opposite edges in parallel.

• Trapezoidal scale: The trapezoid has 2 corners adjacent to the same bottom side or trapezoid with 2 equal diagonal lines.

• Parewasm: The quadrilateral has 2 parallel opposite pairs. In particular, the opposite sides are equal, the angles are equal, the same diagonal intersects at the midpoint of each line. This is a special case of trapezoid.

• Dolixes: This is a special form of the quadrilateral, when there are 4 equal sides.

• Rectangular: The quadrilateral has 4 right angles, with 2 equal diagonal lines and intersect at the midpoint of each line.

• Square: The quadrilateral has 4 equal sides, 4 square angles, with parallel opposite sides, equal and perpendicular diagonal lines at the midpoint. A quadrilateral is a square if and only if it is both a rhombus and a rectangle.

• The inscribed quadrilateral: This is a quadrilateral with all 4 vertices located on the same circle. This is an introverted line with the quadrilateral peaks called Dong Vien, with the center of the circle and the radius is the center of the circumcircle and the participation radius.

Related formulas when learning quadrilateral

Similar to other geometry, the quadrilateral will also have the formula for circumference and basic area. Specifically:

Calculate the circumference

To calculate the perimeter of the quadrilateral, people will add all the edges in the picture together. The general formula calculates the perimeter of the quadrilateral as follows:

P = A + B + C + D

In there:

• P is the perimeter of the quadrilateral
• a, b, c, d are the lengths of the quadrilateral sides, respectively

For example: Calculate the perimeter of the quadrilateral with sides AB = 5cm, BC = 7cm, CD = 9cm and Da = 5cm.

According to the circumference formula we will have the calculation: P = 5 + 7 + 9 + 5 = 26cm.

Acreage

In the quadrilateral, there will be no general formula to calculate the area. Instead, we will rely on each image to be able to deduce different formulas. For example: square area, rectangular area, parallelogram area, … there will be separate formulas.

The types of quadrilateral exercises are common at level 1

For primary school children, the quadrilateral exercises will mainly focus on basic knowledge. Typically:

Form 1: Formula and definition

This is a common type of multiple choice exercises. Often the problem usually gives a definition or formula, requiring students to choose the correct answer related to the given problem.

To solve this exercise, it requires children to understand the knowledge related to the definition, nature, classification and characteristics of each quadrilateral.

For example: The quadrilateral has 4 right angles, with 2 equal diagonal lines and intersect at the midpoint of each line?

A. Square

B. rectangle

C. parallelogram

D. Diamond

Based on the nature and characteristics of the special quadrilateral, it can be inferred to the quadrilateral with 4 right angles, with 2 equal diagonal lines and interrupting at the midpoint of each line, which is the rectangle.

Answer: B

Form 2: Identify the quadrilateral

Because there are many different types in quadrilateral. Therefore, they will be acquainted with the type of exercise to identify the corresponding images.

To solve this exercise correctly, it is necessary to understand the type of quadrilateral, accompanied by the characteristics of each image in detail.

For example: Point out the quadrilateral you see in each of the following images:

Answer:

Form 3: Calculate the circumference/area of ​​the figure

This is one of the common types of exercises. But depending on the type of quadrilateral, the problem given will require students to calculate the circumference, the area of ​​that image according to the given data.

It requires students to understand the circumference formula, the area of ​​each quadrilateral to be able to give an accurate answer.

For example: The quadrilateral ABCD has a circumference of 73cm, knowing the total length of 2 sides AB and BC is 52cm. Calculate the total length of 2 sides CD and leather?

The perimeter of the quadrilateral ABCD is P = AB + BC + CD + DA.

From there 73 = 52 + (CD + DA) = 73 – 52 = 21cm.

Math exercises related to quadrilateral for children to practice

After capturing the theoretical knowledge related to the quadrilateral, here are some practice exercises so that they can apply and practice effectively:

The secret to helping children learn, memorize effective triangular knowledge

Basically, the knowledge related to the quadrilateral also has quite a lot of lessons. So, to help your children can grasp and learn effectively, parents do not ignore the following tips:

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Make sure your baby master the knowledge of the basic quadrilateral

In order for children to solve the exercises correctly, requiring children to master the basic theoretical knowledge from the quadrilateral definition, types, properties, calculation formulas, …

To do this, parents can ask questions for children to answer, check their children’s books, exchange with teachers, and do homework …. Thereby, parents will easily identify their abilities, thereby easily offering teaching plans and supplementing the knowledge that they are weak in time.

Learning with the practice is a prerequisite

After the child has mastered the theory related to the quadrilateral, parents need to practice with them more. The practice here comes from the action with children to do many related exercises in textbooks, review exam questions, refer and practice many exercises on the Internet, organize games, organize competitions for children, study with friends, …

With the more practice, the baby will easily grasp the knowledge, understand the lesson and remember them more effectively. So, parents can take the time to review with their children. Or you can choose Shining Home – Gia đình Anh Ngữ Math so your baby can experience more than 10,000 mathematical interaction activities that are both fun and useful.

Conclude

Above is a summary of the basic knowledge about quadrilateral. This is quite a special picture with many different types. But it is also an important knowledge that parents should guide children to learn in detail to help improve the best learning efficiency.

References

What is a quadrangle?

https://study.com/academy/lesson/What-is-a-quadrangle-definition-shapes.html

Quadrangle (Architecture)

https://en.wikipedia.org/wiki/quadrangle_(architecture)

Nguồn: https://www.ckconitsha.com/vn/ Tác giả: Nguyễn Lân dũng