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Plane figures in the coordinate system

Source: licencja: CC 0.

Figury płaskie w układzie współrzędnych

Learning objectives

  • You will discover the method of calculating the area of polygons drawn in the coordinate system.

Learning effect

  • You read and identify the position of the points in the coordinate system.

  • You calculate the area of the polygons whose vertices are grids.

  • You use English to describe the figures drawn in the coordinate system.

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nagranie abstraktu

Prepare and bring to the class:

- two squared A‑4 size paper sheets,
- the long ruler,
- red pen or crayon.

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nagranie abstraktu

Revise the notion of the coordinate system.

Answer the following question:

  • How can we identify the position of the pointpointpoint in the coordinate system?

  • The students also revise the methods of calculating the areaareaarea of quadrangles and triangles.

Task 1

Identify the figure whose areaareaarea is calculated according to the descriptions below:

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nagranie abstraktu

a) We multiply two adjacent sides.
b) The product of the diagonals is divided by two.
c) We square the length of the side.
d) We multiply the length of the side by the altitude perpendicular to it.
e) The product of the length of the side and the altitude perpendicular to it is divided by two.
f) The product of the sum of the length of the bases and the altitude is divided by two.

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nagranie abstraktu

Today you are going to draw the figures in the coordinate system and calculate their areas.

Task 2
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nagranie abstraktu

Calculate the areaareaarea of the polygon reading the length of the sides of the drawing. Take 1 as the width of one gridgridgrid. If it is necessary, use the method of division into smaller polygons or completing to the larger polygons.

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Source: GroMar, licencja: CC BY 3.0.

Note, that:

  • The areas of the polygons drawn in the coordinate system are calculated in the same way as the polygons drawn in the square gridgridgrid.

Task 3
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nagranie abstraktu

Calculate the areaareaarea of the polygon reading the length of its sides according to the drawing.

a)

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Source: GroMar, licencja: CC BY 3.0.

b)

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Source: GroMar, licencja: CC BY 3.0.

c)

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Source: GroMar, licencja: CC BY 3.0.
Task 4
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nagranie abstraktu

Open the applet. Calculate the areaareaarea of the polygon reading the lengths of its sides according to the drawing. Take 1 as the width of gridgridgrid. Use the method of division into smaller polygons or completing to the larger polygons.

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Geogebra aplet - obliczanie pole wielokąta, odczytując z rysunku długości odpowiednich odcinków. Galeria z opisami alternatywnymi poniżej.
Source: GroMar, licencja: CC BY 3.0.
Task 5

Use squared paper, rulers and red pens.

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nagranie abstraktu

a) Draw the coordinate system and indicate the following points:
A = (4, 4), J = (1, 4), Ń = (0, -4), P = (-5, 2), R = (-4, 4), Y = (0, 2), Z = (-1, 4), Ź = (5, 2).

b) Connect the points by drawing the segments: PR, RZ, ZY, YJ, JA, AŹ, ŹŃ, ŃP in red.

c) Calculate the area of the polygon you have made.

Task 6

An extra task:

a) Indicate the following points in the coordinate system: (3, 8), (5, 8), (5, 7), (7, 7), (7, 5), (5, 5), (5, 2), (6, 2), (8, 0), (5, 0), (3, 2), (0, 2), (-2, 0), (-2, -2), (-4, 0), (-2, 2), (-2, 4), (-4, 4), (-4, 6), (-2, 4).

b) Connect the points drawing the segments in the determined order.

Calculate the area of the figure.

Remember:

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nagranie abstraktu
  • The areas of triangles and quadrangles drawn in the squared net and in the coordinate system can be calculated by reading the length of proper segments on the basis of the drawing.

  • The areas of complex polygons are calculated by using the method of division into smaller polygons or completing to the larger ones.

Check what you have learned by doing the following tasks.

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Determine which sentence is true. Możliwe odpowiedzi: 1. Every isosceles trapezium can be divided into two right triangles and the rectangle. , 2. Every deltoid can be divided into four congruent right triangles., 3. The area of the square equals the half of the product of the length of its diagonals., 4. The area of the right triangle equals the product of the length of its diagonals., 5. The area of the rhombus equals the half of the product of its sides.
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 2

Calculate the area of the polygon below knowing the side of the grid is 1.

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Source: GroMar, licencja: CC BY 3.0.
Exercise 3

a) Draw the coordinate system and indicate the following points: A = (-2, 2), L = (-4, 0), O = (-2, -5), T = (0, 0).

b) Connect the points by drawing the following segments: LA, AT, TO, OL.

c) Calculate the area of the figure you have drawn.

Identify the figure and describe its properties in English.

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Exercise 4
Wersja alternatywna ćwiczenia: Match Polish terms with their English equivalents. punkt Możliwe odpowiedzi: 1. point, 2. method of completing to larger polygons, 3. grid, 4. method of dividing into smaller polygons, 5. area kwadratowa siatka Możliwe odpowiedzi: 1. point, 2. method of completing to larger polygons, 3. grid, 4. method of dividing into smaller polygons, 5. area metoda podziału na mniejsze wielokąty Możliwe odpowiedzi: 1. point, 2. method of completing to larger polygons, 3. grid, 4. method of dividing into smaller polygons, 5. area metoda uzupełniania do większych wielokątów Możliwe odpowiedzi: 1. point, 2. method of completing to larger polygons, 3. grid, 4. method of dividing into smaller polygons, 5. area pole Możliwe odpowiedzi: 1. point, 2. method of completing to larger polygons, 3. grid, 4. method of dividing into smaller polygons, 5. area
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

point
point

punkt

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wymowa w języku angielskim: point
triangle
triangle

trójkąt

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wymowa w języku angielskim: triangle
quadrangle
quadrangle

czworokąt

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wymowa w języku angielskim: quadrangle
area
area

pole

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wymowa w języku angielskim: area
grid
grid

kwadratowa siatka

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wymowa w języku angielskim: grid
method of dividing into smaller polygons
method of dividing into smaller polygons

metoda podziału na mniejsze wielokąty

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wymowa w języku angielskim: method of dividing into smaller polygons
method of completing to larger polygons
method of completing to larger polygons

metoda uzupełniania do większych wielokątów

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wymowa w języku angielskim: method of completing to larger polygons
trapezium
trapezium

trapez

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wymowa w języku angielskim: trapezium
deltoid
deltoid

deltoid

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wymowa w języku angielskim: deltoid

Keywords

pointpointpoint

triangletriangletriangle

quadranglequadranglequadrangle

areaareaarea