This document discusses the basic elements and types of triangles in geometry. It defines a triangle as a shape with 3 vertices, 3 sides, and 3 angles. Triangles are classified based on the lengths of their sides into equilateral, isosceles, and scalene triangles. They are also classified based on the measure of their angles into acute, right, and obtuse triangles. Examples of each type are provided along with their defining properties. An activity asks students to identify different triangles based on the measures of their angles.

1. GEOMETRY
BASIC ELEMENTS AND
TYPES OF TRIANGLES
S.IVRIT SAHANA
22-EDM-04
LOYOLA COLLEGE OF EDUCATION
Chennai-34

2. ACTIVITY
 Now I will give you each with 12 match sticks
 1st you can make a figure with 5 sticks.
 Next with 4 sticks you can make the 2nd figure.
 With 3 sticks you can make a figure.
Now using 3 sticks what shape did you all get ?

3. TRIANGLE

4. BASIC ELEMENTS OF TRIANGLE
1. 3 VERTICES
2. 3 SIDES
3. 3 ANGLES

5. Daily life examples of triangle

6. TYPES AND PROPERTIES OF TRIANGLE
TYPES OF TRIANGLE BASED ON SIDES
1) Equilateral triangle
2)Isosceles triangle
3)Scalene triangle

7. TYPES OF TRIANGLE BASED ON ANGLES
1) Acute angled triangle
2) Right angled triangle
3) Obtuse angled triangle

8. EQUILATERAL TRIANGLE
 If three sides of a triangle are equal in length
, then it is a EQUILATERAL TRIANGLE.

9. ISOSCELES TRIANGLE
 If any two sides of a triangle are equal in length ,
then it is a ISOSCELES TRIANGLE.

10. SCALENE TRIANGLE
 If all the three sides of a triangle are different in its
lengths , then it is a SCALENE TRIANGLE.

11. ACUTE ANGLED TRIANGLE
 If three angles of a triangle are ACUTE ANGLES ,
then it is a acute angled triangle.
 Between 0° and 90°

12. RIGHT ANGLED TRIANGLE
 If an angle of a triangle is a RIGHT ANGLE , then it
is called a right angled triangle.
 Exactly 90°

13. OBTUSE ANGLED TRIANGLE
 If an angle of a triangle is an OBTUSE ANGLE , then
it is an obtuse angled triangle.
 Between 90° and 180°

14. ACTIVITY

15. CAN YOU GUESS THE TRINAGLE?
S.NO angle
A
angle
B
angle
C
Sum of 3
angles
Type of
triangle
1) 60° 60° 60° 180° Acute
angled
triangle
2) 50° 40° 90° 180° Right
angled
triangle
3) 95° 40° 35° 170° No triangle
formed
4) 110° 40° 30° 180° Obtuse
angle
triangle

16. THANK YOU