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The properties of the rhombus

Source: licencja: CC 0.

Własności rombu

Learning objectives

You will discover the properties of the rhombus.

Learning effect

  • You draw the rhombus.

  • You calculate the perimeter of the rhombus.

  • You use English to describe the properties of the rhombus.

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nagranie abstraktu

Cut out of paper models of the square, the rectanglerectanglerectangle, the rhombusrhombusrhombus and the parallelogramparallelogramparallelogram. Choose those that are the rhombuses.

Task 1
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nagranie abstraktu

Measure all the interior angles of the rhombusrhombusrhombus you have prepared for the lesson.

  • What is the relation between the values of the angles which are not situated at the same side?

  • What is the sum of all angles of the rhombus?

  • What is the sum of the anglessum of the anglessum of the angles at the same side?

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nagranie abstraktu

Note that:

  • opposite angles of the rhombusrhombusrhombus are equal.

  • the sum of angles of the rhombus is 360°.

  • the sum of angles at the same side of the rhombusrhombusrhombus is 180°.

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Source: GroMar, licencja: CC BY 3.0.
Task 2
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nagranie abstraktu

Calculate the values of angles of the rhombusrhombusrhombus knowing that one of the angles is 45°.

Task 3
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nagranie abstraktu

Draw a rhombusrhombusrhombus in your notebooks. Then, draw its diagonalsdiagonalsdiagonals.

Follow the instructions:

  • Measure the length of the diagonalsdiagonalsdiagonals.

  • Measure the length of the segments obtained after dividing the diagonalsdiagonalsdiagonals by the intersection point.

  • Measure the angleangleangle of the intersection point.

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nagranie abstraktu

After completing the task answer the following questions:

  • What is the property of the diagonalsdiagonalsdiagonals of any rhombus?

  • What do we know about the diagonals of the rhombusrhombusrhombus?

  • Is it possible for the diagonals to be of the same length?

  • Does the angleangleangle between the diagonals have to be the right one?

  • What is the intersection point of the diagonalsdiagonalsdiagonals of the rhombusrhombusrhombus for each of them?

Task 4
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nagranie abstraktu

Open the applet and watch how the lengths of the diagonalsdiagonalsdiagonals change depending on the position of the vertices.

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Aplet geogebry: Przekątne rombu. Poniżej znajduje się galeria ilustracji stanowiących alternatywę dla apletu.
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

Note that:

The diagonalsdiagonalsdiagonals of the rhombusrhombusrhombus have different lengths, they divide into halves and intersect at the right angleright angleright angle.

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Source: GroMar, licencja: CC BY 3.0.
Task 5
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nagranie abstraktu

Draw two perpendicular straight lines. Mark four points so that they are the vertices of the rhombus with the diagonalsdiagonalsdiagonals of 6 cm and 8 cm. Then, answer the following questions:

  • Into how many parts was the rhombusrhombusrhombus divided by the diagonals?

  • What figures are they?

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nagranie abstraktu

Notice that:

The diagonalsdiagonalsdiagonals divide the rhombusrhombusrhombus into four identical right triangles.

Task 6
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nagranie abstraktu

Calculate the perimeterperimeterperimeter of the rhombusrhombusrhombus with the side of 5 cm.

Task 7
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nagranie abstraktu

An extra task:

Draw the rhombusrhombusrhombus with the perimeterperimeterperimeter of 48 cm and the acute angleacute angleacute angle of 30°.

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nagranie abstraktu

Remember:

  • The rhombusrhombusrhombus is a quadranglequadranglequadrangle with two pairs of parallel sides.

  • Parallel sides of the rhombus are equal.

  • The perimeterperimeterperimeter of the rhombusrhombusrhombus is the sum of all its sides.

  • The opposite angles are of the same value. The sum of the anglessum of the anglessum of the angles at the same side is 180°. The sum of the anglessum of the anglessum of the angles of the rhombus is 360°.

  • The diagonalsdiagonalsdiagonals of the rhombusrhombusrhombus intersect at the centre of their length.

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Complete the sentences. In the rhombus: - all sides 1. are parallel, 2. are equal values, 3. have equal length, 4. 180°, 5. are perpendicular, 6. 360°,
- opposite sides 1. are parallel, 2. are equal values, 3. have equal length, 4. 180°, 5. are perpendicular, 6. 360°,
- opposite angles 1. are parallel, 2. are equal values, 3. have equal length, 4. 180°, 5. are perpendicular, 6. 360°,
- the sum of all angles is 1. are parallel, 2. are equal values, 3. have equal length, 4. 180°, 5. are perpendicular, 6. 360°,
- the sum of angles lying at the same side is 1. are parallel, 2. are equal values, 3. have equal length, 4. 180°, 5. are perpendicular, 6. 360°,
- the diagonals 1. are parallel, 2. are equal values, 3. have equal length, 4. 180°, 5. are perpendicular, 6. 360° to each other.
Exercise 2

Draw the rhombus with the side length of 8 cm. Calculate the perimeter of the rhombus.

Exercise 3

The diagonals divide the rhombus into four identical right triangles. The sides of one of these triangles are: 6 cm, 8 cm, 10 cm. Calculate the lengths of the diagonals and the perimeter of the rhombus.

Describe the properties of the rhombus in English.

Exercise 4
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Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. przekątne - diagonals, 2. romb - rhombus, 3. prostokąt - rectangle, 4. czworokąt - quadrangle, 5. obwód - parallelogram, 6. czworokąt - perimeter
Rzadanie
Source: GroMar, licencja: CC BY 3.0.
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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

acute angle
acute angle

kąt ostry

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wymowa w języku angielskim: acute angle
angle
angle

kąt

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wymowa w języku angielskim: angle
diagonals
diagonals

przekątne

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wymowa w języku angielskim: diagonals
parallelogram
parallelogram

równoległobok – czworokąt, który ma dwie pary boków równoległych

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wymowa w języku angielskim: parallelogram
perimeter
perimeter

obwód

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wymowa w języku angielskim: perimeter
quadrangle
quadrangle

czworokąt

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wymowa w języku angielskim: quadrangle
rectangle
rectangle

prostokąt

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wymowa w języku angielskim: rectangle
rhombus
rhombus

romb – równoległobok, który ma wszystkie boki równe

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wymowa w języku angielskim: rhombus
right angle
right angle

kąt prosty

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wymowa w języku angielskim: right angle
sum of the angles
sum of the angles

suma kątów

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wymowa w języku angielskim: sum of the angles
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Keywords

acute angleacute angleacute angle

parallelogramparallelogramparallelogram

quadranglequadranglequadrangle

rhombusrhombusrhombus

sum of the anglessum of the anglessum of the angles