1. Triangle classification based on angles

2. TRIANGLES (line segments) closed plane figure is called a triangle.
 We have already learnt that a three sided
(line segments) closed plane figure is called a
triangle.
When the three sides of a triangles meet,
they also form three angles. So it is called a

3. Different Types of Triangles
There are several different types of triangles.
You can classify a triangle by its sides and its angles.
There are THREE different classifications for triangles based on their sides.
There are THREE different classifications for triangles based on their angles.

4. Classification based on angles
Acute angled triangle:
If each angle of a triangle is an acute
angle, it is called an acute angled
triangle.
Obtuse angled Triangle:
In a triangle, if one angle is an obtuse
angle, then the triangle is called an
obtuse angled triangle.

5. Right angled Triangle:
In a triangle, if any one angle is a right angle,
then the triangle is called a right angled
triangle.
Q1:- Determine the kind of triangle if the three angles are
Ans:-
In ∆ABC , = 70O , = 60O , = 50O. All the angles in the triangle
are less than 90O. So, ∆ABC is an Acute angled triangle.
ABC
BCA
CAB

6. Q2:- Determine the kind of triangle if the three angles are
Ans:-
In ∆PQR , = 120O , = 40O , = 20O.
So, ∆PQR is an Obtuse angled triangle.
RPQ
PQR
QRP
Q3:- Determine the kind of triangle if the three angles are
Ans:-
In ∆XYZ , = 90O , = 50O , = 40O.
So, XYZ is an Right angled triangle.
XYZ
YZX
ZXY

7. Q4:- Determine the kind of triangle if the three angles are
30O , 100O , 50O
Ans:-
In the triangle, one of the angle is greater than 90O. So, it is an Obtuse angled triangle
Q5:- Determine the kind of triangle if the three angles are
40O , 50O , 90O
In the triangle, one of the angle is 90O. So, it is an Right angled triangle.
Q6:- Determine the kind of triangle if the three angles are
50O , 60O , 70O
In the triangle, all the angles are less than 90O. So, it is an Acute angled triangle

8. Try these Determine the kind of triangle if the three angles are
95O , 60O , 25O
85O , 45O , 50O