Types of triangles based on angles

Acute triangle, obtuse triangle and right triangle are different types of triangles that are formed with different measures of angles.

Objectives

Recognize the triangles based on the measures of the sides

Estimated Time

20 minutes

Prerequisites/Instructions, prior preparations, if any

Prior knowledge of point, lines, angles, elements of triangle

Materials/ Resources needed

• Digital : Computer, geogebra application, projector.
• Non digital : Worksheet and pencil.
• Geogebra files : “Types of triangle by angle.ggb”

Process (How to do the activity)

• Identify the angle types in the triangle.
• Can the angles in the triangle be of different type – obtuse or right angle.
• Establish the types of triangles based on the types of angles that form the triangle – when all angles are acute angles, when one of the angle is a right angle and when one of the angle is obtuse angle.
• Is it possible to have a triangle with two right angle or two obtuse angle. Why or why not?
• What kind of a triangle is formed when all the angles are equal? For what measure of the angle such a triangle is formed?
• Can a triangle be formed with a reflex angle.
• Measure the angles for different triangle, recognize the types of angles and conclude the type of triangle.

Observation	Angle 1 measure and its Type	Angle 2 measure and its Type	Angle 3 measure and its Type	What can you say about angles?	Type of triangle formed
Triangle 1
Triangle 2
Triangle 3

Evaluation at the end of the activity

• Are children able to recognize the types of triangles based on the angles in a triangle.