# Linear pair axiom : If a ray stands on a line, then the sum of two adjacent angles so formed is 180 degrees

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Two adjacent angles are said to be form a linear pair of angles, if their non-common arms are two opposite rays. Linear pair axiom of theorems are if a ray stands on a line , then the sum of two adjacent angles so formed is 180 degree

### Objectives

Introduce children to linear pair of angles

### Estimated Time

30 minutes

### 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 : “Linear pair axiom - ray on a line.ggb”

Download this geogebra file from this link.

### Process (How to do the activity)

- Prior hands on activity
- Start with coinciding point C with the point B
- What is the angle formed by the line
- Move point C above and slowly rotate around point 0
- How many angles do you notice
- Name the angles formed : what are their measure
- Do the two angles together form a 180
^{o}angle - Do the two angles form a linear pair
- Record the values of the two angles for various positions of point C

Sl No. ∠BOA ∠BOC ∠COA ∠BOC + ∠COA Dothe angles form a linear pair .

**Evaluation at the end of the activity**