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Let's learn the types of triangle:
Triangles can be classified based on its sides as well as its angles.
Types of triangles based on its side lengths are as follows.
- Equilateral triangle
- Isosceles triangle
- Scalene triangle
A triangle is an equilateral when all its sides are equal in length.
![Theory3.1.png](https://resources.cdn.yaclass.in/d4817f6d-34e8-49d2-87bd-a13d3a19cd7d/Theory31w300.png)
Example:
![Theory3.2.png](https://resources.cdn.yaclass.in/5dc2e5a1-46ba-46d7-8106-96d6da911fab/Theory32w300.png)
In here, the sides are equal in measure \(AB=BC=CA=5\) units.
A triangle is isosceles when two of its sides are equal in length.
![Theory3.3.png](https://resources.cdn.yaclass.in/2f9d4406-83c9-4570-814a-75323e85d465/Theory33w300.png)
Example:
![Theory3.4.png](https://resources.cdn.yaclass.in/1e01c34a-7f08-4c5a-b5f7-a865d109d85f/Theory34w300.png)
In here, the two of the sides are equal in measure \(AB=CA=1\) unit and \(BC=√2\) units.
A triangle is a scalene when all the three sides are unequal.
![Theory3.5.png](https://resources.cdn.yaclass.in/dcc7fd19-f7a4-489f-b47a-fb820af6f081/Theory35w300.png)
Example:
![Theory3.6.png](https://resources.cdn.yaclass.in/c74f286a-1ed0-4284-93fc-9813c8d93956/Theory36w300.png)
In here, all the sides are unequal in measure \(AB=7.7, CA=5\) units and \(BC=9\) units.
Types of triangles based on its angles are as follows.
- Acute angled triangle
- Right angle triangle
- Obtuse angled triangle
A triangle is acute angle triangle when all the three of its angle are acute (less than 90°).
![Theory3.7.png](https://resources.cdn.yaclass.in/60883eb4-a1e2-45a8-a538-fd616d5d603a/Theory37w300.png)
Example:
![Theory3.8.png](https://resources.cdn.yaclass.in/52d6a1b3-eebd-41d3-911e-1e1fc10a3b8d/Theory38w300.png)
In here, all the three angles are less than \(90°\). That is, \(∠A=60°, ∠B=50°\) and \(∠C=70°\).
A triangle is right angle triangle when one of its angles is a right angle (90°), and the other two are acute angles (less than 90°).
Example:
![Theory3.10.png](https://resources.cdn.yaclass.in/005d02b7-5df5-4001-874b-3ba152688526/Theory310w200.png)
In here, one among the angle is \(90°\), and the other two are acute. That is, \(∠A=40°, ∠B=50°\) and \(∠C=90°\).
A triangle is an obtuse angle triangle when one of its angles is an obtuse angle (greater than 90°), and the other two are acute angle (less than 90°).
![Theory3.11.png](https://resources.cdn.yaclass.in/e57edfaa-600e-4202-bc38-bd5fb05b19a4/Theory311w300.png)
Example:
![Theory3.12.png](https://resources.cdn.yaclass.in/702d6c99-56b9-438d-a2ce-3193e7da15a4/Theory312w300.png)
In here, one among the angle greater than \(90°\) and the other two are acute. That is, \(∠A=120°, ∠B=35°\) and \(∠C=25°\).