Regular Polygons & GeoGebra

Kids, No More Shame! GeoGebra Comes To School! GeoGSeries# Episode #01

J3
KidsTronics
9 min readSep 10, 2020

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Hi, last day, my son comes to me with these 10 math exercises to solve:/

I use this:

https://www.geogebra.org/classic/k5zb3twm.

Are you curious about what is GeoGebra? Welcome!

There you have it all math questions:

EX_01: A square inscribed on a circumference has an area worth 12 square meters; How big is the side of this square? What is its radius?
Fig 1. EX_01: What is the length of the side (s)? And the radius (r)?
EX_02: a square inscribed on a circumference with the radius equal to r = 3+(ROOT(36)/2); tell us, under these conditions, what is the measure of the apothem and length of the side of this polygon?
Fig 2. EX_02: What is the apothem? and the Perimeter?
EX_03: Given a regular hexagon inscribed on a circumference and knowing that this hexagon has a side equal to 4.5cm and apothem equal to 39/10; tell us, what is the area of that hexagon?
Fig 3. EX_03: The Area of the hexagon is?
EX_04: Determine the measure of the central angle, the interior angle, and the number of diagonals of the following regular polygons: a) triangle; b) Heptagon, and c) Decagon?
Fig 4. EX_04: What are the central, interior angles, and the number of diagonals of these polygons?
EX_05: It is known that:
a) The circumference has a radius of 6cm;
b) the triangle (SOR) has an area of 17.12cm^2.
The question is: what is the measure of the shaded area of the figure?
Fig 5. EX_05: An pentagon and a [ SOR] Triangle.
 EX_06: Check  V for true and F for false to the alternatives below:
a)( ) Is the diagonal of a polygon a line segment that joins opposite vertices of a polygon?
b)( ) If the side of a square is 15cm, then its area is equal to 60cm^2?
c)( ) If the apothem of a regular pentagon is equal to 8.3cm and the side of the pentagon is equal to 12cm, then the perimeter of that pentagon is 60cm.
d)( ) the formula to find the area of a circle is equal to A = pi times diagonal?
e)( ) Is the central angle of a polygon equal to the measure of the interior angle?

That one is just made of questions. Just playing around with GeoGebra to get it easily!

EX_07: a pendulum of 15cm in length oscillates between points A to B describing an angle of 15°. What is the length of the path described by its end between A and B?
Fig 6. EX_07: a pendulum of 15 degrees between points A and B.
EX_08: determine the size of an arc with a central angle measuring 22° contained in a circumference of radius equal to 10cm.
Fig 7. EX_08: What is the length of this arc?
EX_09: Determine, in centimeters, the area of the figure below:
Fig 8. EX_09: What is the size of the area enclosed by the arches and lines?
EX_10: Having a 10cm radius pizza, Maria ate a 35° circumference ring; in relation to that, say, what area of the pizza did Maria eat?
Fig 9: EX_10: What is the size of the Piece of Pizza?

Oops! You know what? How far back can your memory go?

I find out that I am not able to complete this assignment within a tight timeframe…

It took me all day long to solve it by hand :/

Here’s How To Fix That: GeoGebra!

That’s it!

And this post is all about GeoGebra!

GeoGebra has become the leading provider of dynamic mathematics software, supporting science, technology, engineering, arts, and mathematics (STEAM*) education and innovations in teaching and learning worldwide (see its Awards and Abouts).

*STEAM (Science, Tech, Engineer, Art, and Math)

Call GeoGebra anytime!

Never again will we forget anything or even that blessed apothem’s formula…

Just like a math pro, with these quick and easy steps, that I present now, we’ll solve these math problems in a way that you can never imagine it is possible to (and will give you the power to make infinite others questions, to leverage your child’s study!):

In 5 minutes!

Ooh, yeah! say what? say what? say what?

Five minutes! That’s it! Yeah, it is really amazing!

This is a real challenge that I impose on myself! Be my guest!

Trigger Chrono now!

A cool welcome!

00 #Step — See the solution for all problems here:

There is something excellent in GeoGebra, impressive really!

Let me show you how to get started quickly in a step-by-step fashion!

01 #Step — Ex_01 Solved!

EX_01: A square inscribed on a circumference has an area worth 12 square meters; How big is the side of this square? What is its radius?
Geo 1. EX_01 solved! In no time! try these steps yourself at the link above:)

(1) Set n to 4;

(2) Looking for the Area(egon*), then (3) reset the r until you get 12 as the value of the area of the polygon (or approximation; use the arrow in the keyboards to get as close as possible!) ;

*egon = Abstract Regular Polytopes (a geometric object with flat sides) - Egon Schulte

(4)The result of the Length of a side of the egon is 3.46 and (3) the radius is 2.45.

Let’s confirm it by the formulas provided:

For calculation of the Area of the comics:

Calc 1.0. For calculation of the radius using the Area Formula. 2,25! Bang!
Calc 1.1. For the polygon EX_01, everything is alright! Next question, the clock is ticking…

02 #Step — EX_02 Solved!

EX_02: a square inscribed on a circumference with the radius equal to r = 3+(ROOT(36)/2); tell us, under these conditions, what is the measure of the apothem and length of the side of this polygon?
Geo 2. EX_02 solved! In no time!

(1) Set r to 6;

(2) There you have it: The Apothem is 4.24!

(3) The length of the side of the square is 8.49!

Let’s confirm it by the formulas provided:

For calculation of the Apothem & and length of this polygon:

Calc 2. For the polygon EX_02, everything is checked! I warning that there is not much time…

03#Step — EX_03 Solved!

EX_03: Given a regular hexagon inscribed on a circumference and knowing that this hexagon has a side equal to 4.5cm and apothem equal to 39/10; tell us, what is the area of that hexagon?
Geo 3. EX_03 solved! In no time!

(1) Set n to 6;

(2) Now reset the r until you get the Apothem to 3.9 and the Radius will be 4.5;

(3) There you have it: The Area of the hexagon is 52.61!

Let’s confirm it by the formulas provided:

For calculation of the Apothem & Perimeter:

Calc 3. For the polygon EX_03; our answers are satisfactory and sufficient!

04 #Step — EX_04 Solved!

EX_04: Determine the measure of the central angle, the interior angle, and the number of diagonals of the following regular polygons: a) triangle; b) Heptagon, and c) Decagon?

First for the Triangle:

Geo 4_1. EX_04_a solved! In no time!

(1) Set n to 3 and (2) r to 10 for better visualization :);

(3) There you have it: The Triangle Central Angle is 120°!

(4) There you have it: The Triangle Interior Angle is 60°!

(5) There you have it: The Triangle N° of Diagonals is Zero!

Now for the Heptagon:

Geo 4_2. EX_04_b solved! In no time!

(1) Set n to 7;

(2) There you have it: The Heptagon Central Angle is 51.43°!

(3) There you have it: The Heptagon Interior Angle is 128.57°!

(4) There you have it: The Heptagon N° of Diagonals is 14!

Now for the Decagon:

Geo 4_3. EX_04_c solved! In no time! Your students now have the geometric figure with the questions answered: fantastic! See what central, internal angles mean? Diagonal lines are combinations of lines, vertices to vertices …Easy, right? Come on, next question…

(1) Set n to 10;

(2) There you have it: The Decagon Central Angle is 36°!

(3) There you have it: The Decagon Interior Angle is 144°!

(4) There you have it: The Decagon N° of Diagonals is 35!

Let’s confirm it by the formulas provided:

Calc 4. For the polygon EX_04; nothing complicated, is it?

05 #Step — EX_05 Solved!

EX_05: It is known that:
a) The circumference has a radius of 6cm;
b) the triangle (SOR) has an area of 17.12cm^2.
The question is: what is the measure of the shaded area of the figure?

The Pentagon:

Fig 10. EX_05: An hexagon and a [ SOR] Triangle.
Geo 5. EX_05_c solved! In no time!

(1) Set n to 5 and r to 6;

(2) There you have it: The Conic Area 113.1!

(3) There you have it: The Polygon Area 85.6!

(4) There you have it: The Remaining areas 27.5!

Let’s confirm it by the formulas provided:

Calc 5. For the polygon EX_05; Check the Answer! Next…

6 #Step — EX_06 Solved!

Just playing with GeoGebra and you can answer those questions in a few seconds …Try it yourself!

EX_06: Check  V for true and F for false to the alternatives below:
a)( V ) Is the diagonal of a polygon a line segment that joins opposite vertices of a polygon?
b)( F ) If the side of a square is 15cm, then its area is equal to 60cm^2?
c)( F ) If the apothem of a regular pentagon is equal to 8.3cm and the side of the pentagon is equal to 12cm, then the perimeter of that pentagon is 60cm.
d)( F ) the formula to find the area of a circle is equal to A = pi times diagonal?
e)( F ) Is the central angle of a polygon equal to the measure of the interior angle?

07#Step — EX_07 Solved!

EX_07: a pendulum of 15cm in length oscillates between points A to B describing an angle of 15°. What is the length of the path described by its end between A and B?
Geo 7. The answer to this question is in the following GeoGebra Activity: Angles & Pendulus!

08#Step — EX_08 Solved!

EX_08: determine the size of an arc with a central angle measuring 22° contained in a circumference of radius equal to 10cm.
Geo 8. Just use the tools provided by the GeoGebra interface! Piece of cake, isn’t it?

09#Step — EX_09 Solved!

EX_09: Determine, in centimeters, the area of the figure below:
Fig 11. EX_09: the size of areas delimiter by the arcs.

Here is the answer to the Area_1 is 9.24!

Geo 9_1. The calculation for the first circle; 15° + 15° = 30°, radius =3; result 9.24cm the black area!

And here is the answer to Area_2 is 2.96!

Geo 9_2. The result = 9.24 + 2.96 = 12.2 cm

This question at first seemed easy, but maybe I was wrong

It turned out to be a bit complicated … but Geogebra solved it! Check it out!

10#Step —EX_10 Solved!

EX_10: Having a 10cm radius pizza, Maria ate a 35° circumference ring; in relation to that, say, what area of the pizza did Maria eat?
Geo 10. Maria ate 30.54 cm²!

This is kidStronics!

I am J3, The Arduino Hobbyist! Your host!

I hope that you as a teacher or parent, like me, have realized the potential of using this incredible tool in class or at home: GeoGebra!

Now please consider opening an account there!

It’s fast and I bet you’ll become an instant fan!

Enjoy it!

Thank You For Reading This Post!

Comments? Welcome any of them: positive or negative! interact more, please!

See you in the next #GeoGSeries Episode!

By for now o/

Download All Files for This Project

References & Credits

Regular Polygons by wikipedia.org

Egon Schulte by https://en.wikipedia.org/wiki/Egon_Schulte

Online Calculator by https://www.calculatorsoup.com/calculators/geometry-plane/polygon.php

Related Posts:

01# Episode — GeoGSeriesRegular Polygons & GeoGebra — Kids, No More Shame! GeoGebra Comes To School! (this one, for while:)

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J3
KidsTronics

Hi, Guys o/ I am J3! I am just a hobby-dev, playing around with Python, Django, Ruby, Rails, Lego, Arduino, Raspy, PIC, AI… Welcome! Join us!