Ed. Tech. Project

1. Prepared by:
Chellsea M. Arig
Kaye L. Fernandez
John Oscar M. Sanchez

2. Objectives:
 I can define what is a triangle.
 I can classify the triangle according to it’s type.
 I can construct the different types of triangles.

3. What is a triangle?
- is a polygon with three vertices and three sides
(edges).
- it has three internal angles which has a sum of
180 degrees.
- the symbol of a triangle is ∆.

4. TYPES OF TRIANGLES
According to Sides
• Isosceles triangle
• Equilateral triangle
• Scalene triangle
According to Angles
• Acute triangle
• Right triangle
• Obtuse triangle
Triangles can be classified into two types:

5. According to Angles

6. Types of Triangles
• Acute triangle
- when all the angles of a triangle are less than 90
Example:
where; ∠ABC, ∠ACB and ∠BAC are all acute angles

7. Types of Triangles
 Right triangle
- a triangle in which one of the three angles is a
right angle
Example:
where; ∠ABC = one right angle

8. Types of Triangles
• Obtuse triangle
- a triangle where one of the three angles is
more than a right angle (or is an obtuse angle)
Example:
where; ∠ABC is an obtuse angle

9. According to Sides

10. Types of Triangles
• Isosceles triangle
- a triangle having a pair of its sides or two
line-segments equal
Example:
where; AB = AC.
equal sides

11. Types of Triangles
• Equilateral triangle
- a triangle having all the three line-segments
or sides equal
Example:
where; AB = BC = CA

12. Types of Triangles
• Scalene triangle
- a triangle having all the three line-segments
or sides unequal
Example:
where; AB ≠ BC ≠ AC

13. Evaluation
I. Directions: Classify the following triangles
accordingly.
1.
2.
3.
Triangle Angle Side

14. II. Directions: Construct an acute
isosceles triangle using any
straight edge material.
( Equivalent of 2 points.)

15. References
 http://www.mathexpression.com/types-of-triangles.html
 https://en.wikipedia.org/wiki/Triangle
 http://www.brighthubeducation.com/middle-school-
math-lessons/39674-triangle-properties-and-angles/