PDF chapter test TRY NOW
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/b919f8a0-9b56-4b63-8d60-7944de90b459/Theory31w300png.png)
Example:
![Theory3.2.png](https://resources.cdn.yaclass.in/32f671c2-aba7-462e-9812-34501e950bb5/Theory32w300png.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/f5a70bdf-8695-445e-a00f-3ff10634883f/Theory33w300png.png)
Example:
![Theory3.4.png](https://resources.cdn.yaclass.in/1ae0410a-37ef-40a3-91c0-db0ccacf4c14/Theory34w300png.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/612e072b-b114-47ef-af5e-824fa7bde9ea/Theory35w300png.png)
Example:
![Theory3.6.png](https://resources.cdn.yaclass.in/bcd07f39-96db-4cda-b361-21438e822431/Theory36w300png.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/0c3460fb-c395-41a4-b64d-200ed4c3eea8/Theory37w300png.png)
Example:
![Theory3.8.png](https://resources.cdn.yaclass.in/5cd0da84-07a5-4605-9549-ac1d83df400d/Theory38w300png.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/e6d64198-7ca3-4c4a-87d0-6511b2429036/Theory310w200png.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/0216fa3e-5317-407d-a25c-3336ba21043e/Theory311w300png.png)
Example:
![Theory3.12.png](https://resources.cdn.yaclass.in/5039a547-4200-4b83-a1ff-183c811f0e21/Theory312w300png.png)
In here, one among the angle greater than \(90°\) and the other two are acute. That is, \(∠A=120°, ∠B=35°\) and \(∠C=25°\).