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.

What is a line segment?

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

Angle what is it?

An angle is formed by two non collinear rays with a common endpoint.

Acute Angle Right Angle

Obtuse Angle

Vertex

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.

Triangles Classified according to SIDES

SCALENE TRIANGLE

E

D

F

No two of its sides are congruent.

ISOSCELES TRIANGLE

G

H

I

At least two of its sides are congruent.

G

H

I

Vertex angle – common

endpoint of two rays

Leg Leg

Base angle Base angle

EQUILATERAL TRIANGLE

J

K

L

All sides are congruent.

Triangles Classified according to ANGLES

ACUTE TRIANGLE

M

N

O

All of its angles are acute.

RIGHT TRIANGLE

P

Q

R

It has one right angle.

Acute Angle

Acute Angle

Hypotenuse- longest side and it is

side opposite the right angle.

Right AngleLeg

Leg

OBTUSE TRIANGLE

S

T

U

One of its angle is obtuse.

EQUIANGULAR TRIANGLE

X

V

W

All of its angles are congruent.