Pentagons
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Basics on the topic Pentagons
What are Pentagons?
Before we talk about the pentagon shape, let’s talk about the type of shape a pentagon is. Are pentagons quadrilaterals? No, a quadrilateral is a shape that has four sides. First, it is important to note that a pentagon the shape, is a polygon. A polygon is a two-dimensional shape that is made of straight lines and is fully closed. What is a pentagon shape? A pentagon is a five-sided polygon. How many sides does a pentagon have? A pentagon has five sides with the penta- in the word pentagon meaning five, as in five sides.
Pentagons – Definition
Pentagons can be defined by three attributes. In order for a shape to be identified as a pentagon, it must have ALL of the defining attributes:
| # | Attribute |
|---|---|
| 1 | Five straight sides |
| 2 | Five vertices |
| 3 | A fully closed shape |
Now that we know what polygon has 5 sides, let’s answer some questions about pentagons.
How Many Sides are on a Pentagon?
In other words, a pentagon has how many sides? In order for a shape to be classified as a pentagon it must have five straight sides. However, it’s not just about the pentagon sides, it must have two more attributes as well!
How Many Angles Does a Pentagon Have?
A pentagon must also have five vertices or corners, which are also referred to as angles. There is one more attribute a shape must have in order to be classified as a pentagon.
What Does a Pentagon Look Like?
Pentagons must also have one last attribute. It must be a fully closed shape. That means all sides must meet to make corners or angles, without leaving any sides open.
Pentagons – Attributes
Is this shape a pentagon? Let’s take a look at the attributes.
It has five straight sides…
five vertices…
and is fully closed!
This shape is a pentagon!
Pentagons – Summary
A pentagon is a five-sided polygon. Pentagons can be defined by three attributes. In order for a shape to be identified as a pentagon, it must have ALL of the 3 defining attributes:
| # | Attribute |
|---|---|
| 1 | Five straight sides |
| 2 | Five vertices |
| 3 | A fully closed shape |
Want to practise identifying pentagons? In this video you can find identifying pentagons examples and on this website there are worksheets along with other activities, and interactive exercises.
Transcript Pentagons
Nico and Nia are at the arcade and just found their favorite game, the claw machine! However, this is a special kind of claw machine. It only releases prizes that are shaped like a pentagon. Let's help Nico and Nia identify pentagons in the claw machine by answering the question, "What is a Pentagon?" A pentagon is a special type of shape. Shapes are figures that we can name based on their defining properties, or traits that make them unique. A POLYGON, is a two-dimensional shape that is made of straight lines and is fully closed. A PENTAGON, is a five-sided polygon. In order for a shape to be identified as a pentagon, it must have ALL of the following properties: Five straight sides, five vertices, and be fully closed. THIS shape is a pentagon because it has five straight sides, five vertices, and is fully closed. Now that we know the properties of a pentagon, let's help Nico and Nia identify pentagon prizes in the claw machine! The first prize they've picked is a bubble fidget toy, is it a pentagon? Let's check. How many sides does it have? It has FOUR straight sides. How many vertices? There are FOUR vertices. Is it fully closed? Yes, it is a fully closed shape. Even though this shape has one of the properties, it is NOT a pentagon. Remember, in order to be a pentagon, it must have ALL the properties. Next, we see a headband. Is it a pentagon? It has FIVE sides, and they are all straight. How many vertices does it have? There are FOUR vertices. Is it fully closed? It is NOT a closed shape. The headband does not have ALL of the defining properties, so it is NOT a pentagon. Last, we see a gemstone sticker, what a treasure! Is this shape a pentagon? It has five sides, five vertices, and is fully closed! It has ALL the defining properties! This shape IS a pentagon, so Nico and Nia get to keep this prize! Before we see if Nico and Nia will get more prizes, let's summarize. Remember, a pentagon is a polygon with five sides. In order for a shape to be identified as a pentagon, it must have ALL of the defining properties: five straight sides, five vertices, and be fully closed. Oh, the claw machine picked up a soccer ball! Uh oh, I think the claw might be too sharp to hold that, look out Nico and Nia! Phew! I'm glad they are okay! "Yes! Now we get to keep all the toys!" "You're such a gem, Nia."
Pentagons exercise
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What are the properties of a pentagon?
HintsCan you count the sides?
Can you count the vertices?
Do all of the sides join up, or are there any gaps?
SolutionA pentagon has 5 straight sides.
A pentagon has 5 vertices.
A pentagon is a closed shape.
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Find the pentagons.
HintsDoes it have 5 sides and 5 vertices?
Is it a closed shape?
There are 4 correct options.
SolutionThese shapes are pentagons because they:
- have 5 sides.
- have 5 vertices.
- are closed shapes.
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What could Nico and Nia get?
HintsWhich items have 5 sides?
Which items have 5 vertices?
There are 4 pentagon-shaped items.
SolutionHere are the pentagon-shaped items highlighted in violet:
- the diamond sticker.
- the Pop It.
- the pencil sticker.
- the sweet.
- they all have 5 sides.
- they all have 5 vertices.
- they are all closed shapes.
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Which items are pentagons?
HintsCount the number of sides and vertices. How many should there be if it is a pentagon?
Is it a closed shape?
Remember, pentagons can face in any direction.
SolutionThese items are all pentagons because:
- they all have 5 sides.
- they all have 5 vertices.
- they are all closed shapes.
-
How many pentagons can you see here?
HintsDoes the shape have 5 sides?
Does the shape have 5 vertices?
Here is an example of a pentagon.
SolutionThere are 4 pentagons in this picture. Here they are highlighted in green.
They all:
- have 5 sides.
- have 5 vertices.
- are closed shapes.
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How many pentagons can you see?
HintsHow many sides must a shape have to be a pentagon?
How many vertices must a shape have to be a pentagon?
All pentagons are:
- 5-sided shapes.
- shapes with 5 vertices.
- closed shapes.
Solution- The house has 4 pentagons.
- The boat has 3 pentagons.
- The necklace has 5 pentagons.
- The sign has two pentagons.
