# Different Types of Triangles: A Vocabulary Guide for English Learners

Sharing is caring!

Triangles are one of the most basic and fundamental shapes in geometry. But did you know that there are actually several different types of triangles, each with its own unique properties and characteristics? In this article, we’ll explore the world of triangles and take a closer look at different types of triangles. We’ll examine the defining features of each type, including their side lengths and angles, and explore some real-world examples of where you might encounter these triangles in your everyday life. Whether you’re a math enthusiast or simply curious about the world around you, this guide to the types of triangles is sure to expand your knowledge and appreciation of this fascinating shape.

Types of Triangles Contents

## Types of Triangles: Basic Understanding

Triangles are one of the most basic and important shapes in geometry. They are polygons with three sides and three angles. In this section, we will explore the different types of triangles, their properties, and how to classify them.

### Types of Triangles

There are three types of triangles based on the length of their sides:

• Scalene Triangle: A scalene triangle has no equal sides.
• Isosceles Triangle: An isosceles triangle has two equal sides.
• Equilateral Triangle: An equilateral triangle has three equal sides.

There are also three types of triangles based on the measure of their angles:

• Acute Triangle: An acute triangle has all angles less than 90 degrees.
• Right Triangle: A right triangle has one angle that measures exactly 90 degrees.
• Obtuse Triangle: An obtuse triangle has one angle that measures more than 90 degrees.

### Properties of Triangles

Triangles have several important properties that are useful to know:

• The sum of the angles in a triangle is always 180 degrees.
• The longest side of a triangle is opposite the largest angle, and the shortest side is opposite the smallest angle.
• The altitude of a triangle is a line segment from a vertex perpendicular to the opposite side.
• The median of a triangle is a line segment from a vertex to the midpoint of the opposite side.

### Classifying Triangles

To classify a triangle, you can use the length of its sides or the measure of its angles. For example, a triangle with two equal sides is an isosceles triangle, while a triangle with all acute angles is an acute triangle. Knowing how to classify triangles is important for solving geometry problems and understanding the properties of shapes.

## Types of Triangles

Triangles are one of the most basic shapes in geometry, and they come in different types. In this section, we will explore the three main types of triangles: Equilateral, Isosceles, and Scalene.

### Equilateral Triangle

An equilateral triangle is a type of triangle where all three sides are equal in length. This means that all three angles are also equal, and each angle measures 60 degrees. Here are some examples of equilateral triangles:

• The sides of an equilateral triangle can be of any length, as long as they are all equal.
• An equilateral triangle can also be called an equiangular triangle because all its angles are equal.

### Isosceles Triangle

An isosceles triangle is a type of triangle where two sides are equal in length, and the third side is different. This means that two angles are also equal, and the third angle is different. Here are some examples of isosceles triangles:

• In an isosceles triangle, the two equal sides are called legs, and the third side is called the base.
• The angle between the two legs is called the vertex angle, and the other two angles are called base angles.

### Scalene Triangle

A scalene triangle is a type of triangle where all three sides are different in length. This means that all three angles are also different. Here are some examples of scalene triangles:

• A scalene triangle can have any combination of angles and side lengths, as long as all three sides are different.
• In a scalene triangle, the longest side is opposite the largest angle, and the shortest side is opposite the smallest angle.

## Properties of Triangles

### Angles

Triangles have three angles, and the sum of these angles is always 180 degrees. The angles of a triangle can be classified based on their measure as acute, right, or obtuse angles. Here are some examples:

Angle Type Measure (in degrees)
Acute Less than 90
Right Exactly 90
Obtuse Greater than 90

### Sides

Triangles have three sides, and the length of these sides can be used to classify triangles into different types. The following table shows the different types of triangles based on the length of their sides:

Triangle Type Description
Scalene No sides are equal in length
Isosceles Two sides are equal in length
Equilateral All three sides are equal in length

### Vertices

The vertices of a triangle are the points where the sides of the triangle meet. The number of vertices a triangle has depends on the type of triangle. Here are some examples:

Triangle Type Number of Vertices
Scalene 3
Isosceles 3
Equilateral 3

## Real Life Examples of Triangles

Triangles are one of the most common shapes found in our daily lives. Here are some real-life examples of triangles:

### Architecture

Architects use triangles extensively in their designs. Triangles are used to create stability and strength in structures, such as bridges and buildings. For example, the Eiffel Tower in Paris is a great example of a structure that uses triangles to provide stability.

### Art

Triangles are also used in art. Artists use triangles to create a sense of balance and harmony in their work. For example, the famous painting “The Last Supper” by Leonardo da Vinci uses triangles to create a sense of balance and harmony.

### Sports

Triangles are often used in sports. For example, in soccer, the ball is kicked into the goal, which is shaped like a triangle. In basketball, the court is shaped like a triangle, and the three-point line is also a triangle.

### Mathematics

Triangles are an important part of mathematics. They are used in geometry to calculate angles, sides, and areas. For example, the Pythagorean theorem is used to calculate the length of the sides of a right triangle.

### Everyday Objects

Triangles are found in many everyday objects. For example, pizza slices are triangular, and traffic signs are often triangular in shape. The musical instrument, the tambourine, is also shaped like a triangle.

## Triangle Vocabulary

Triangles are simple shapes with three sides and three angles. They are one of the most basic shapes in geometry and are used in many different areas of mathematics and science. In this section, we’ll cover some important vocabulary related to triangles.

### Types of Triangles

Based on the length of their sides, triangles can be classified into three types:

• Scalene triangle: a triangle with no congruent sides.
• Isosceles triangle: a triangle with two congruent sides.
• Equilateral triangle: a triangle with three congruent sides.

### Types of Angles

Triangles can also be classified based on the measure of their angles:

• Acute triangle: a triangle with all angles measuring less than 90 degrees.
• Right triangle: a triangle with one right angle (measuring 90 degrees).
• Obtuse triangle: a triangle with one angle measuring greater than 90 degrees.

### Parts of a Triangle

Every triangle has three sides and three angles. In addition, there are some other important parts of a triangle:

• Vertex: the point where two sides of a triangle meet.
• Altitude: a line segment drawn from a vertex to the opposite side, perpendicular to that side.
• Hypotenuse: the longest side of a right triangle, opposite the right angle.

### Triangle Inequality Theorem

The Triangle Inequality Theorem states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. In other words, if a, b, and c are the lengths of the sides of a triangle, then:

• a + b > c
• b + c > a
• a + c > b

### Pythagorean Theorem

The Pythagorean Theorem is a formula that relates the lengths of the sides of a right triangle. If a and b are the lengths of the legs of a right triangle, and c is the length of the hypotenuse, then:

• a^2 + b^2 = c^2

### Examples

Here are some examples of triangles:

Type of Triangle Description
Scalene triangle A triangle with sides of length 3, 4, and 5.
Isosceles triangle A triangle with sides of length 5, 5, and 7.
Equilateral triangle A triangle with sides of length 6, 6, and 6.
Acute triangle A triangle with angles measuring 60, 60, and 60 degrees.
Right triangle A triangle with angles measuring 30, 60, and 90 degrees.
Obtuse triangle A triangle with angles measuring 110, 35, and 35 degrees.

What are the 3 types of triangles based on sides?

The three types of triangles based on sides are scalene, isosceles, and equilateral.

What are the types of triangles based on sides and angles?

Based on sides and angles, the types of triangles are:

• Scalene triangle: All three sides have different lengths and all angles are different.
• Isosceles triangle: Two sides are equal in length and two angles are equal.
• Equilateral triangle: All three sides are equal in length and all angles are equal.

What are the types of triangle on the basis of angles?

Based on angles, the types of triangles are:

• Acute triangle: All angles are less than 90 degrees.
• Obtuse triangle: One angle is greater than 90 degrees.
• Right triangle: One angle is exactly 90 degrees.

What are the properties of a scalene triangle?

The properties of a scalene triangle are:

• All sides have different lengths.
• All angles have different measures.
• The longest side is opposite to the largest angle.
• The shortest side is opposite to the smallest angle.

What is an obtuse triangle?

An obtuse triangle is a triangle where one angle is greater than 90 degrees.

What are the 4 types of triangles and their properties?

The four types of triangles and their properties are:

Type of Triangle Properties
Scalene All sides have different lengths and all angles are different.
Isosceles Two sides are equal in length and two angles are equal.
Equilateral All sides are equal in length and all angles are equal.
Right One angle is exactly 90 degrees.

The three types of triangles based on sides are scalene, isosceles, and equilateral.

Based on sides and angles, the types of triangles are:

\n

\n
• Scalene triangle: All three sides have different lengths and all angles are different.
• \n

• Isosceles triangle: Two sides are equal in length and two angles are equal.
• \n

• Equilateral triangle: All three sides are equal in length and all angles are equal.
• \n

Based on angles, the types of triangles are:

\n

\n
• Acute triangle: All angles are less than 90 degrees.
• \n

• Obtuse triangle: One angle is greater than 90 degrees.
• \n

• Right triangle: One angle is exactly 90 degrees.
• \n

The properties of a scalene triangle are:

\n

\n
• All sides have different lengths.
• \n

• All angles have different measures.
• \n

• The longest side is opposite to the largest angle.
• \n

• The shortest side is opposite to the smallest angle.
• \n

An obtuse triangle is a triangle where one angle is greater than 90 degrees.

The four types of triangles and their properties are:

\n

\n

\n

\n

\n

\n

\n

\n

\n \n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

\n

Type of Triangle Properties
Scalene All sides have different lengths and all angles are different.
Isosceles Two sides are equal in length and two angles are equal.
Equilateral All sides are equal in length and all angles are equal.
Right One angle is exactly 90 degrees.

"}}]}