1. Objectives:
Within the timeframe the students will be able to:
• identify the kinds of triangle;
• name the basic parts of a triangle;
• classify triangles according to its side and
angles;
• measures the sides and angles of given
triangles;
• cooperate actively in a given task.

2. What is a line segment?
A line segment is a part of a line
consisting two endpoints and all the
points between them.

3. Angle what is it?
An angle is formed by two non collinear
rays with a common endpoint.

4. Acute Angle Right Angle

5. Obtuse Angle
Vertex

6. A carpenter cut different
triangles with different sizes.
He wanted to classify these
according to sides and angles
and he found difficult in doing
it.

7. Triangles Classified
according to SIDES

8. SCALENE TRIANGLE
E
D
F
No two of its sides are congruent.

10. ISOSCELES TRIANGLE
G
H
I
At least two of its sides are
congruent.

11. Leg Leg
G
H
Vertex angle
– common
endpoint of
two rays
I
Base angle
Base angle

12. EQUILATERAL TRIANGLE
J
K
L
All sides are congruent.

14. Triangles Classified
according to
ANGLES

15. ACUTE TRIANGLE
M
N
O
All of its angles are acute.

17. RIGHT TRIANGLE
Q
P
R
It has one right angle.

18. Acute Angle
Hypotenuse-longest
side and it is
side opposite the
right angle.
Acute Angle
Right Angle
Leg
Leg

20. OBTUSE TRIANGLE
S
T
U
One of its angle is obtuse.

22. EQUIANGULAR TRIANGLE
X
V
W
All of its angles are congruent.