Regular and Irregular Polygons | Grade 7 | Matatag Curriculum | Quarter 1 |

Summary

In this educational video, the instructor, JMJ, introduces the concept of polygons, focusing on regular and irregular polygons with 5, 8, and 10 sides. The video clarifies what makes a figure a polygon and distinguishes between regular polygons, where all sides and angles are equal, and irregular ones, where they are not. The instructor demonstrates how to draw regular polygons using a protractor and ruler, providing examples of regular pentagons, hexagons, octagons, and decagons, as well as their irregular counterparts. The lesson aims to help students understand the fundamental properties of polygons and their variations.

Takeaways

• 📐 A polygon is a closed figure with straight sides in a two-dimensional plane.
• 🔍 The first illustration is not a polygon due to the presence of a curved side.
• 🔎 The second illustration is not a polygon as it is an open figure missing a side.
• 🎯 The third illustration is a polygon because it is closed and made up of straight line segments.
• 🔑 A regular polygon has all sides and angles of equal measure, while an irregular polygon does not.
• 📝 Regular polygons can be drawn using a protractor and ruler to ensure equal sides and angles.
• 📈 A pentagon is a polygon with five sides, and a regular pentagon has five equal sides and angles.
• 🔶 A hexagon has six sides, and a regular hexagon has six equal sides and angles.
• 🔟 An octagon has eight sides, and a regular octagon has eight equal sides and equal interior angles.
• 📊 A decagon has ten sides, and a regular decagon has ten equal sides with congruent interior angles.
• 🚫 Irregular polygons, such as the irregular pentagon and hexagon, have sides and angles that are not equal.
• 👋 The video concludes with an invitation to like, share, and subscribe to help more students learn about polygons.

Q & A

What is a polygon?

A polygon is a closed figure made up of line segments, not curves, in a two-dimensional plane.

Why is illustration number one not considered a polygon?

Illustration number one is not a polygon because it has a curve side, and polygons are made up of line segments only.

Why can illustration number two not be classified as a polygon?

Illustration number two is not a polygon because it is an open figure, lacking a complete line segment to form a closed shape.

What is the correct answer to identify a polygon in the given illustrations?

The correct answer is number three, as it is a closed figure made up of line segments.

What is a regular polygon?

A regular polygon is a polygon where all sides are equal in length and all interior angles are of equal measure.

What is an irregular polygon?

An irregular polygon is a polygon that does not have equal sides and equal angles.

How many sides does a pentagon have?

A pentagon has five sides.

What is a hexagon?

A hexagon is a polygon with six sides.

What distinguishes a regular pentagon from an irregular pentagon?

A regular pentagon has five equal sides and five equal angles, while an irregular pentagon does not have equal sides or angles.

How many sides does an octagon have?

An octagon has eight sides.

How many sides does a decagon have?

A decagon has ten sides.

What is the difference between a regular octagon and an irregular octagon?

A regular octagon has eight equal sides and eight equal interior angles, whereas an irregular octagon has sides and angles that are not equal.

What tool did the teacher use to ensure the sides and angles of the polygons were equal?

The teacher used a protractor and a ruler to ensure that the polygons had equal sides and angles.

How can one learn to draw regular polygons?

One can learn to draw regular polygons by following step-by-step instructions, which can be found in the video class linked in the description.

Outlines

00:00

📐 Introduction to Polygons and Regular Polygons

The video begins with an introduction to polygons, defining them as closed figures composed of line segments in a two-dimensional plane. The instructor, JMJ, clarifies that a polygon cannot have curved sides or be an open figure. Three illustrations are presented to the class for identification, with the third illustration correctly identified as a polygon due to its closed shape and straight sides. The video then delves into the concept of regular polygons, which are polygons with equal sides and equal angles, contrasting them with irregular polygons that do not have these properties. The instructor uses illustrations to demonstrate the characteristics of regular and irregular polygons, highlighting that regular polygons have congruent sides and angles, while irregular ones do not. The video concludes with an invitation for viewers to learn how to draw regular polygons using a protractor and ruler, with a promise of a detailed explanation in a subsequent video.

05:02

🔍 Exploring Regular and Irregular Polygons with More Sides

In the second paragraph, the focus shifts to polygons with eight and ten sides, known as octagons and decagons, respectively. The instructor explains the characteristics of a regular octagon, which has eight equal sides and eight equal interior angles, using a visual aid to show that each side measures 5 cm. Similarly, a regular decagon is described, with each of its ten sides measuring 4 cm and all interior angles being congruent. The video then contrasts these with irregular octagons and decagons, where the sides and angles are not equal, thus not meeting the criteria for regularity. The instructor emphasizes the importance of understanding the difference between regular and irregular polygons and encourages students to share the video to help more learners. The video ends with a farewell from Teacher MJ, who invites viewers to have a great day.

Keywords

💡Polygon

A polygon is a two-dimensional shape with straight sides that are connected to form a closed figure. In the video, the teacher emphasizes that a polygon must be made up of line segments, not curves, and must be a closed figure. The script uses illustrations to differentiate between figures that are and are not polygons, highlighting the importance of having both straight sides and a closed shape.

💡Regular Polygon

A regular polygon is a specific type of polygon where all sides and all interior angles are equal. The video script explains that regular polygons have a uniform appearance because of their symmetry. Examples from the script include a regular pentagon and a regular hexagon, both of which have sides of equal length and angles of equal measure.

💡Irregular Polygon

An irregular polygon is a polygon where the sides and angles are not all equal. The script contrasts this with regular polygons, using illustrations to show polygons with sides of varying lengths and angles of different measures. The irregular pentagon and hexagon in the script serve as examples of this type of polygon.

💡Pentagon

A pentagon is a polygon with five sides. The script introduces the concept of a regular pentagon, which has five equal sides and five equal angles. The teacher uses a regular pentagon as an example to demonstrate the properties of regular polygons.

💡Hexagon

A hexagon is a polygon with six sides. The video script discusses regular hexagons, which have six congruent sides and six congruent angles. The concept is used to illustrate the characteristics of a regular polygon with a higher number of sides than a pentagon.

💡Octagon

An octagon is a polygon with eight sides. The script explains the properties of a regular octagon, which has eight equal sides and eight equal interior angles. This serves to further the understanding of regular polygons with an even higher number of sides.

💡Decagon

A decagon is a polygon with ten sides. The video script describes a regular decagon, which has ten congruent sides and ten congruent interior angles, to illustrate the concept of regular polygons with an even number of sides.

💡Protractor

A protractor is a tool used to measure angles. In the script, the teacher mentions using a protractor to ensure that the angles in a regular polygon are equal. This tool is essential for drawing accurate regular polygons.

💡Ruler

A ruler is a measuring instrument used to determine lengths. The script describes using a ruler to ensure that all sides of a regular polygon are of equal length, highlighting the importance of precision in drawing regular polygons.

💡Congruent

Congruent, in the context of geometry, means identical in shape and size. The script uses the term to describe sides and angles that are equal in length or measure within regular polygons, such as the regular pentagon, hexagon, octagon, and decagon.

💡Interior Angles

Interior angles are the angles formed inside a polygon by two adjacent sides. The script explains that in a regular polygon, all interior angles are congruent, meaning they are equal to each other, which is a key characteristic of regular polygons.

Highlights

Introduction to the topic of regular and irregular polygons.

Definition of a polygon as a closed figure with line segments in a two-dimensional plane.

Illustration and identification of a polygon with three given examples.

Explanation of why the first and second illustrations are not considered polygons.

Confirmation that the third illustration is a polygon due to its closed figure made of line segments.

Introduction of the term 'pentagon' for a polygon with five sides.

Differentiation between regular polygons with equal sides and angles, and irregular polygons.

Illustration of regular polygons with equal sides and angles.

Instruction on how to draw regular polygons using a protractor and ruler.

Explanation of a regular pentagon with five equal sides and angles.

Introduction of the term 'hexagon' for a polygon with six sides.

Description of a regular hexagon with six congruent sides and angles.

Illustration and explanation of an irregular pentagon with unequal sides and angles.

Introduction of the term 'octagon' for a polygon with eight sides.

Description of a regular octagon with eight congruent sides and angles.

Introduction of the term 'decagon' for a polygon with ten sides.

Explanation of a regular decagon with ten congruent sides and angles.

Illustration and explanation of an irregular octagon with eight unequal sides and angles.

Illustration and explanation of an irregular decagon with ten unequal sides and angles.

Conclusion summarizing the lesson on regular and irregular polygons.

Invitation to like, share, and subscribe for more educational content.

Transcripts

Hi guys good day It's me jmj our topic

for today class It's all about regular

and regular polygons And we're focusing

on 5 si 8 or 10 ses so without further

Ado let's do this topic now before we

discuss with regular and regular

polygons let's define first What is a

polygon now a polygon is a close figure

made up of line segments not curves in a

two dimensional plane so I have here

given three illustration class and you

identify which of the following

illustration is a polygon now if your

answer is number three that's correct

This is a polygon now for number one

class we cannot call this one a polygon

because it has a curve side this

particular side is a curve side

therefore This is not a polygon because

a polygon is made up of line segments

not curves now for number two can we

call this one a polygon Nope we cannot

call this one a polygon because it is an

open figure We don't have this

particular side So this is not a polygon

now for number three can we call this

one a polygon Yup This is a polygon

because it's made up of line segments

and it is a closed figure So if you have

a close figure made up of line segments

a two dimensional plane therefore this

one is a polygon now we call this one

class a pentagon a polygon with five

sides we call that one of pentagon so 1

two 3 4 f now if you understand the

polygon class Let's talk about regular

and regular polygons regular polygons

all sides are equal and all angles are

of equal measure while irregular

polygons are polygons that do not have

equal sides and equal angles now based

on this given illustration class what

have you noticed that's correct on the

first and second illustration they have

equal sides as well as they have equal

angles now the third and fourth

illustration the sides are not equal and

the angles are not equal so once again

if they have equal sides and equal

angles we call this one regular polygons

I actually draw this one class using the

protractor and The ruler so that they

will have the same side as well as they

will have the same angle so the next

part of a video Class is how to draw

regular polygons using the protractor

and The ruler and we will Explain that

one class is step by step so feel free

to see the video class I will just put

the link on the description down below

so once again class this one we call

this one regular pentagon because this

side is equal to This side and This side

is equal to This side they have all

equal sides and their angles are also

equal So this angle right here is

congruent to this angle to this angle

this angle and this angle five equal

sides five equal angles we call this one

regular pentagon So this one Hexagon

pentagon with six sides now call this

one regular Hexagon if six sides are

equal six angles six inter angles are

equal so once again This side is

congruent to This side to This side they

have six congruent

sides and six congruent angles we call

this one regular

Hexagon All right now for this one class

we call this one irregular pentagon it

has five sides we call this one pentagon

but it is irregular pentagon because

this particular sides is not equal as

well as their angles so based on the

figure class you can see that this

angles are not equal as well as the

sides This side Okay is shorter to This

side and this is the longest side so

they don't have the same side class so

we call this one irregular pentagon same

with this one irregular Hexagon we have

six sides so one so Let's count the

number of sides one two three four

five then si six sides and the sides are

not equal as well as the angle so we

call this one irregular Hexagon so I

hope you understand class with regards

to regular polygons and a regular

polygon so let's have another example

class 8 and 10 sides so the octagon and

the decagon so let's have another

example CL for the illustration Now

let's proceed now for the eight sides

and 10 sides once again class a polygon

with eight sides we call this one

octagon a polygon with with 10 sides we

call it decagon so I have here regular

octagon once again regular octagon it

has eight equal sides and eight equal

interior angles So if this is 5 cm for

the sides therefore This is also 5 cm 5

cm 5 cm so This side is congruent to

This side This side This side This side

and This side This side the side so

eight congruent sides eight equal sides

and for the angles interior angles must

be also congruent So this angle All

right So this angle will be congruent to

this angle So this angle will be

congruent to this angle to this angle so

eight inter your angles are congruent

All right and for this one regular

decagon If This is 4 CM This is also 4

CM 4 CM 4 CM all sides must be congruent

for the regular decagon so 10 sides are

congruent of course the interior angles

is also

congruent All right So this angle right

here is also

congruent now for this one class we have

irregular octagon it has eight sides so

Let's count the number of sides so 1 2 3

4 5 6 7 then 8 so eight sides are not

congruent as well as the angles They are

not congruent so we call that irregular

Octagon

so We also have irregular decagon so

Let's count the number of sides so one

two one then two 3 then 4 then 5 then 6

7 8 then 9 then 10 so 10 sides 10 sides

are not congruent as well as the

interior angles so we call it one

irregular decagon so I hope you learn

something new today class with regards

to regular and regular polygons Do not

forget to like share and subscribe you

share to your friends and classmates so

that we can help more students once

again this is teacher MJ you have a

great day CL Goodbye for now Byebye