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Pyramid and its properties

Source: licencja: CC 0.

Ostrosłup i jego własności

Learning objectives

You will learn about the types of pyramids.

You will learn the elements of the pyramid: the edges of the base, side edges, height, angles.

Learning effect

  • You determine the types of pyramids.

  • You indicate the elements of the pyramid.

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nagranie abstraktu

Review your knowledge of relative position of the two planes, the relative position of the two lines in space and the relative position of the line and the plane.

The aim of the lesson is to learn about the properties of the pyramidpyramidpyramid.

Task 1
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nagranie abstraktu

Analyze the material contained in the applet. Formulate the definition of a pyramidpyramidpyramid.

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Aplet geogebra: Sześciokątny ostrosłup. Poniżej znajduje się galeria będąca wersją alternatywną dla aplikacji.
Source: GroMar, licencja: CC BY 3.0.
A pyramid
Definition: A pyramid
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nagranie abstraktu

pyramidpyramidpyramid is a polyhedron formed by connecting a polygonal basebasebase and a point, called the apexapexapex. Each base edgeedgeedge and apexapexapex form a triangle, called a lateral face. It is a conic solid with a polygonal base.

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nagranie abstraktu

Determine the relationship between the type of the n‑sides of the basebasebase and the number of faces, vertices and edges of the pyramid. Formulate appropriate conclusions.

Task 2
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nagranie abstraktu

The base of the pyramid is the n‑sided polygon. Identify the relationship between the number n and the number of vertices, edges and faces of the pyramidpyramidpyramid.

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nagranie abstraktu

pyramidpyramidpyramid with an n‑sided basebasebase has:

  • n + 1 vertices,

  • n + 1 faces,

  • and 2n edges.

The pyramid is called a right one
Definition: The pyramid is called a right one
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nagranie abstraktu

The pyramid is called a right one if all its lateral edges have the same length.

The pyramid is the regular pyramid
Definition: The pyramid is the regular pyramid
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nagranie abstraktu

The pyramidpyramidpyramid is the regular pyramidregular pyramidregular pyramid if its basebasebase is a regular polygon.

The trigonal or triangular pyramid
Definition: The trigonal or triangular pyramid
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nagranie abstraktu

The trigonal or triangular pyramid with all equilateral triangle faces is the regular tetrahedron.

Using the definitions solve the problems.

Task 3
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nagranie abstraktu

In a pyramidpyramidpyramid, the number of faces is 7 less than the number of edges. Calculate how many vertices this pyramid has.

Task 4
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nagranie abstraktu

In the regular quadrangular pyramidpyramidpyramid the length of the base edge is equal to 4 dm, and the side edgeedgeedge length is 6 dm. Calculate the heightheightheight of this pyramid.

Task 5
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nagranie abstraktu

In the regular triangular pyramid the edge of the basebasebase is 10 dm long, the side edgeedgeedge is 8 dm. Calculate the heightheightheight of this pyramid.

Task 6
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nagranie abstraktu

Calculate the measure of the dihedral angle at the basebasebase of the triangular pyramidpyramidpyramid if the height of the pyramid is 3 times shorter than the heightheightheight of the base.

Task 7
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nagranie abstraktu

The sum of the edge length of a regular tetrahedron is equal to 48 cm. Calculate the heightheightheight of this tetrahedron.

Task 8
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nagranie abstraktu

The base of the right pyramidright pyramidright pyramid is a rectangle with sides of 8 cm and 10 cm. The side edgeedgeedge length is 15 cm. Calculate the heights hIndeks dolny 1 and hIndeks dolny 2 of the two different side faces of this pyramidpyramidpyramid.

Task 9

Task for volunteers:

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nagranie abstraktu

The basebasebase of the pyramid is the square, and the bottom of its heightheightheight is in one of the vertices of this square. Knowing that the height of the pyramidpyramidpyramid is equal to the diagonal of the base, calculate the cosine of the inclination angle of the longest side edge of the pyramid to the edgeedgeedge of the base.

Do the revision exercises.

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nagranie abstraktu
  • The pyramidpyramidpyramid is a polyhedron formed by connecting a polygonal basebasebase and a point, called the apexapexapex. Each base edgeedgeedge and apexapexapex form a triangle, called a lateral face. It is a conic solid with polygonal base.

  • The pyramid is called a right one if all its lateral edges have the same length.

  • The pyramid is the regular pyramidregular pyramidregular pyramid if its basebasebase is a regular polygon.

Exercises

Exercise 1
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Wersja alternatywna ćwiczenia: The pyramid has 24 edges. The number of faces of this pyramid is equal to: Możliwe odpowiedzi: 1. 8, 2. 12, 3. 13, 4. 23
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 2

The base of the pyramid is a right‑angled triangle, whose sides are 6 cm long and 8 cm long. All faces of the pyramid are inclined to the plane of the base at an acute angle α such that tgα=158.

Calculate the height of this pyramid.

Exercise 3

In your notebook describe the properties of pyramids in English.

Exercise 4
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Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. ostrosłup - a pyramid, 2. ostrosłup prosty - a right pyramid, 3. ostrosłup prawidłowy - a regular pyramid, 4. podstawa ostrosłupa - a pyramid base, 5. krawędź boczna ostrosłupa - a lateral face of the pyramid, 6. wierzchołek ostrosłupa - a pyramid height
zadanie
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

angle of inclination of the lateral face to the base
angle of inclination of the lateral face to the base

kąt nachylenia ściany bocznej ostrosłupa do podstawy

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wymowa w języku angielskim: angle of inclination of the lateral face to the base
apex
apex

wierzchołek (ostrosłupa)

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wymowa w języku angielskim: apex
base
base

podstawa (ostrosłupa)

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wymowa w języku angielskim: base
edge
edge

krawędź

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wymowa w języku angielskim: edge
height
height

wysokość (ostrosłupa)

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wymowa w języku angielskim: height
lateral edge of the pyramid
lateral edge of the pyramid

krawędź boczna ostrosłupa

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wymowa w języku angielskim: lateral edge of the pyramid
lateral face of the pyramid
lateral face of the pyramid

ściana boczna ostrosłupa

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wymowa w języku angielskim: lateral face of the pyramid
pyramid
pyramid

ostrosłup

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wymowa w języku angielskim: pyramid
right pyramid
right pyramid

ostrosłup prosty

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wymowa w języku angielskim: right pyramid
regular pyramid
regular pyramid

ostrosłup prawidłowy

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wymowa w języku angielskim: regular pyramid

Keywords

lateral face of the pyramidlateral face of the pyramidlateral face of the pyramid

pyramidpyramidpyramid

basebasebase

regular pyramidregular pyramidregular pyramid

right pyramidright pyramidright pyramid