Difference between revisions of "Interior and exterior angles in triangle"
Jump to navigation
Jump to search
| Line 23: | Line 23: | ||
* Note the measure of angles | * Note the measure of angles | ||
{| class="wikitable" | {| class="wikitable" | ||
| − | ! | + | ! colspan="3" |Angles of the triangle |
| − | ! | + | ! colspan="3" |Exterior angle |
| − | ! | + | ! colspan="3" |Interior angle + Exterior angle |
| − | + | |- | |
| − | + | |Angle 1 | |
| − | + | |Angle 2 | |
| + | |Angle 3 | ||
| + | |Angle 1 | ||
| + | |Angle 2 | ||
| + | |Angle 3 | ||
| + | |In Angle 1 | ||
| + | + | ||
| + | |||
| + | Ex Angle1 | ||
| + | |In Angle 2 | ||
| + | + | ||
| + | |||
| + | Ex Angle2 | ||
| + | |In Angle 3 | ||
| + | + | ||
| + | |||
| + | Ex Angle3 | ||
|- | |- | ||
| | | | ||
| Line 36: | Line 52: | ||
| | | | ||
| | | | ||
| − | |||
| | | | ||
| | | | ||
| | | | ||
| + | |- | ||
| | | | ||
| | | | ||
| | | | ||
| − | |||
| | | | ||
| | | | ||
Revision as of 05:12, 12 April 2019
Objectives
- Identify all angles when a triangle is formed
- Understand the relation between various angles that are formed in a triangle.
Estimated Time
Prerequisites/Instructions, prior preparations, if any
Prior knowledge of point, lines, angles
Materials/ Resources needed
- Digital : Computer, geogebra application, projector.
- Non digital : Worksheet and pencil.
- Geogebra files : “Angles of triangle.ggb”
Process (How to do the activity)
- Ask students how many lines are there? They should be able to identify the points of intersection of the lines. How many points of intersection are formed?
- How many angles are formed at an intersecting point? How many angles in total at the three points of intersection?What is the total angle measure at each intersecting point?
- How many angles are inside the triangle and how many are outside the triangle
- Can you find an exterior angle that is equal to the interior angle of a triangle at each vertex?Why are they equal?
- Identify the exterior angles that are equal? Justify why they are equal.
- Establish that there are 2 angles which are exterior of the triangle that are equal and are formed when the sides of the triangle is extended at the vertex.
- Students to analyze the interior and exterior angle at each point to find a relation between the interior angle and one of the exterior angles at the vertex. Students should be able to recognize the linear pair formed by interior angle and exterior angle.
- Vary the position of the lines to check if interior and exterior angles form a linear pair.
- Note the measure of angles
| Angles of the triangle | Exterior angle | Interior angle + Exterior angle | ||||||
|---|---|---|---|---|---|---|---|---|
| Angle 1 | Angle 2 | Angle 3 | Angle 1 | Angle 2 | Angle 3 | In Angle 1
+ Ex Angle1 |
In Angle 2
+ Ex Angle2 |
In Angle 3
+ Ex Angle3 |
Evaluation at the end of the activity
- Are students able to recognize interior and exterior angles in a triangle
- Have the students able to find a relation between the interior angle and exterior angle that are formed at each vertex?