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Math for Kids23 chapters | 325 lessons

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Lesson Transcript

Instructor:
*Ashley Pettway*

Ashley is a Special Education teacher who loves inquiry-based, hands-on learning!

Triangles may be a simple shape but there are lots of different types! In this lesson, we will clearly define a triangle and think about some of the different kinds of triangles.

Triangles are very common shapes. We see them on road signs, on houses, and in food (think chips or pizza). When you think of a triangle, you might imagine three equal sides because we see this type of triangle a lot in our daily lives, but did you know that there are lots of different types of triangles? Triangles can be stretched out and tall like the Eiffel Tower or short and squished like a hanger. What are some other examples of different types of triangles that you can think of?

All types of triangles can be grouped or categorized. Triangles are categorized by the length of their sides and the size of their angles. Before we get into the different types of triangles, take a minute and think about what a triangle is. (Hint: 'tri' means three)

Simply put a **triangle** is a shape with three sides and three angles. With a definition that simple, there are bound to be lots of different kinds. As we explore all the different types of triangles, remember the three must-haves for a shape to be a triangle. The shape must have:

- 3 sides
- 3 angles
- All of the angles add up to 180 degrees

Like we talked about before, triangles are categorized by the length of their sides and the size of their angles. First let's look at the three different categories of triangles based on the length of their sides.

**Equilateral**: All sides are equal. All angles are equal.**Isosceles**: Two sides are equal. Two angles are equal.**Scalene**: No sides are equal. No angles are equal.

Now let's move on to the angles. An **angle** is the space between two lines that connect and form a point. In this case, angles are where the sides of the triangles meet. Angles are measured in degrees. These degrees are not like temperature, they measure how big or small an angle is, not how hot or cold it is outside.

If an angle is less than 90 degrees, it is an acute angle. If an angle is bigger than 90 degrees, it is an obtuse angle. Think of 90 degrees as the sweet spot.

**Acute**: All angles are less than 90 degrees.**Obtuse**: One angle is greater than 90 degrees.**Right**: One angle equals 90 degrees.

Remember, a triangle is categorized by its sides and its angles so a triangle can be both an equilateral and acute or scalene and obtuse.

Let's review. **Triangles** have three sides and three angles. All three angles must add up to 180 degrees. Triangles can be categorized by their sides (**equilateral, isosceles**, or **scalene**) and by their angles (**acute, right**, or **obtuse**). Triangles have a simple definition but there are lots of different kinds for you to build and explore!

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Math for Kids23 chapters | 325 lessons

{{courseNav.course.topics.length}} chapters | {{courseNav.course.mDynamicIntFields.lessonCount}} lessons | {{course.flashcardSetCount}} flashcard set{{course.flashcardSetCoun > 1 ? 's' : ''}}

- Surface Area Lesson for Kids
- Types of Angles: Lesson for Kids
- Types of Triangles: Lesson for Kids
- Geometric Shapes: Lesson for Kids
- Isosceles Triangle Lesson for Kids
- How to Use a Protractor: Lesson for Kids
- 3-D Shapes: Lesson for Kids
- Pentagon Shapes: Lesson for Kids
- Polygon Shapes: Lesson for Kids
- Diamond Shapes: Lesson for Kids 2:42
- Measuring Angles: Lesson for Kids
- Circle Definition: Lesson for Kids 3:10
- Circumference Lesson for Kids: Definition & Formula
- Cubes: Lesson for Kids
- Properties of a Circle: Lesson for Kids
- Rectangle Definition: Lesson for Kids
- Triangle Lesson for Kids: Definition & Facts 3:06
- How to Find the Area of a Triangle: Lesson for Kids
- How to Find the Volume of a Cylinder: Lesson for Kids
- Pentagon Shape Facts: Lesson for Kids 2:39
- Vertices: Lesson for Kids
- What is a Regular Polygon? - Lesson for Kids
- Pythagorean Theorem Proof: Lesson for Kids
- Pythagorean Theorem Lesson for Kids: Definition & Examples
- How to Find the Perimeter of a Regular Pentagon 2:43
- Is a Pentagon a Regular Polygon?
- Geometry Definition: Lesson for Kids
- Names of Polygons
- What is a Venn Diagram? - Lesson for Kids 3:32
- Triangle Sum Theorem Proof
- Facts About Right Angles
- Octagon Lesson for Kids: Definition & Facts
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- Perimeter Lesson for Kids: Definition & Examples
- 4-Sided Polygons 3:55
- Dodecahedron: Definition & Facts
- Special Right Triangles: 3-4-5 Triangle
- Triangle Sum Theorem: Definition & Examples
- Dodecahedron: Patterns & Properties
- Finding the Area of an Irregular Hexagon 3:38
- How to Divide an Angle into Two Equal Angles
- What is a Congruent Angle? - Lesson for Kids
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