SUBJECT TEACHER: MR. JERICHO B. NADANZA
GRADE 8 - MATH

Let’s make a TRIANGLE
GeoGebra.com

Situation:
You have 2 Sets of Sticks in your hand
and you need to connect it form a Triangle .
Set A Sticks is made up of 3 sticks measures,
10 cm , 9cm , 5cm and Set B Sticks is made
up of 3 sticks also measures 9cm , 6cm , 2
cm

PROCESS QUESTIONS
1. What have you observed in Set A Sticks can
they form a triangle?
2. What have you observed in Set B Sticks can
they form a triangle?

Fill the table below
A + B
A + C
B + C
In SET A, 10cm, 9 cm, 5 cm
Let A = 10
Let B = 9
Let C = 5
In SET B, 9cm, 6cm, 2 cm
Let A = 9
Let B = 6
Let C = 2
10+9
10+5
9 + 5
19
15
14
C = 5
B = 9
A =10
>
>
>
A + B
A + C
B + C
9+6
9 + 2
6 + 2
15
11
8
C = 2
B = 6
A =9
>
>
<

Base on activity, What can you say about making
Triangle?
How can we say that the 3 given sides are the sides
of the Triangle?

Triangle Inequality Theorem

Triangle Inequality Theorem
In any Triangle, the sum of the
lengths of any two of its sides is greater
than the length of its third side.

Determine if each set of segments can
form a TRIANGLE.
Example 1. 9 cm, 6 cm, 2 cm
9 + 6 =
9 + 2 =
6 + 2 =
15
8
11
2
6
9
>
>
<
NOT a TRIANGLE

Determine if each set of segments can
form a TRIANGLE.
Example 1. 15 cm, 12 cm, 16cm
15 + 12 =
15+ 16 =
12 + 16 =
27
28
31
16
12
15
>
>
>
A TRIANGLE

Lets Try it in QUIZIZZ….

Triangle Inequality Theorem
In any Triangle, the sum of the
lengths of any two of its sides is greater
than the length of its third side.
GENERALIZATION