The document defines and describes the different parts and types of triangles. It discusses the primary parts of a triangle including sides, angles, and vertices. It then describes the secondary parts such as the median, altitude, and angle bisector. The document outlines the different types of triangles according to their angles, including acute, obtuse, right, and equiangular triangles. It also defines triangle types according to their sides, such as scalene, isosceles, and equilateral triangles. In the end, it provides an activity to test the reader's understanding of these triangle concepts.

1. Prepared by: Elizer S. Sampang

2. CONTENTS
Meaning of the Triangle
Parts of the Triangle
- Primary Parts
- Secondary Parts
Kinds of Triangle
- According to Angles
- According to Sides

3. A polygon with
three sides, three
angels and three
vertices.
It is the union of
three non collinear
points.

4. The sum
of the
interior
angles are
180
degrees.

7. Sides
- AB, BC, CA
Angles
- A, B, C
Vertices
- A, B, C
A
C B

9. Median
- is the segment drawn from one
vertex of a triangle to the midpoint of the
opposite sides.
A
B C
D
AD -
BD = DC

10. Altitude
- is the perpendicular segment
drawn from one vertex of the triangle to
the line containing the opposite side.
Altitude - AC

11. Angle Bisector
- is the segment drawn from one
vertex and dividing the angle into two
congruent angles.
AP - Angle bisector
BAP = CAP

14.  Acute Triangle
- is a triangle with three angles are
less than 90.
Examples:
50
70
60
59
66 55

15.  Obtuse Triangle
- is a triangle with one of the angle
is more than 90.
Examples:
110
20
50

16.  Right Triangle
- is a triangle
with one angle is
exactly 90.
- the longest side
is the hypotenuse and
the two sides are the
legs.
Example:

17.  Equiangular Triangle
- is a triangle with all angles are
congruent.
60
60 60
Example:

19.  Scalene Triangle
- is a triangle with no equal
sides.
Examples:
5m
8m
7m
5m
3m
4m

20.  Isosceles Triangle
- is a triangle with two sides
are congruent.
Examples:
12cm 12cm
15cm
4
4
8

21.  Equilateral Triangle
- is a triangle with all sides
are congruent.
Example:
6cm 6cm
6cm

22. Parts Kinds
Primary Secondary
 Sides
 Angles
 Vertices
 Median
 Altitude
 Angle
bisector
Angles Sides
 Acute
 Obtuse
 Right
 Equiangular
 Scalene
 Isosceles
 Equilateral

23. ACTIVITY
A. Identify the following.
1. A triangle with two equal sides.
2. A triangle whose one of its angle is
more than 90 degrees.

24. 3. A triangle whose angles are less than 90
degrees.
4. A triangle where all of its angle are
congruent.
5. A triangle with no equal sides.