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### Course: 7th grade foundations (Eureka Math/EngageNY)>Unit 6

Lesson 2: Topic B: Foundations

# Types of triangles review

Review ways to classify triangles based on their sides lengths and angles.  Practice classifying triangles.

## Classifying triangles by their angles

### Acute triangles

An $\text{acute}$ triangle has $\text{3 angles that}$ . Below are examples of $\text{acute triangles}$.

### Right triangles

A $\text{right}$ triangle has and $2$ acute angles. Below are examples of $\text{right triangles}$.

### Obtuse triangles

An $\text{obtuse}$ triangle has $\text{one angle that measures}$ and $2$ acute angles. Below are examples of $\text{obtuse triangles}$.
Problem 1A
Classify $\mathrm{△}PQR$ by its angles.

Want to try more problems like this? Check out this exercise

## Classifying triangles by their side lengths

### Equilateral triangles

An $\text{equilateral}$ triangle has $\text{three equal sides}$. Below are examples of $\text{equilateral}$ triangles.

### Isosceles triangles

An $\text{isosceles}$ triangle has $\underset{―}{\text{at least}}$ $\text{two equal sides}$. Below are examples of $\text{isosceles}$ triangles.

### Scalene triangles

A $\text{scalene}$ triangle has $\text{no equal sides}$. Below are examples of $\text{scalene}$ triangles.
Problem 2A
Classify $\mathrm{△}PQR$ by its sides.

Want to try more problems like this? Check out this exercise.

## Want to join the conversation?

• Why can't I go back to selecting? I got a wrong and I can't go back
• It just won't let you.
• why is the isosceles triangle and the equilateral both classified as each other
• because an equilateral triangle is all equill sides and an isosceles triangle is two or more equill sides
• Is their any more triangle practices?
• No. You will have to do them over if you want extra practice.
• Why are triangles used in math?
• it is because it uses geometry
• I don’t understand why an equilateral triangle is constantly being defined as and Isosceles triangle.
• An equilateral triangle has 3 equal length sides. An isosceles triangle has at least 2 sides of the same length. Thus all equilateral triangles are also isosceles.
• if all of the angels are acute but lenghths are different what is that?
• its scalene
• i got my one right but it said i got it worng
• I... I think that means you got it wrong, but you don't understand. You might want to check your answer or ask someone else to explain it to you.