# Parallel lines

Relation between angles that are formed in multiple parallel lines is investigated with geogebra sketch.

### Objectives

To understand corresponding angles are equal

To understand  alternate angles are equal

30 minutes

### Prerequisites/Instructions, prior preparations, if any

Prior knowledge of point, lines, angles, intersecting lines, vertically opposite angles

### Materials/ Resources needed

• Digital : Computer, geogebra application, projector.
• Non digital : Worksheet and pencil.
• Geogebra files : Parallellines-3.ggb

### Process (How to do the activity)

• Use the file to seek the initial observations from children – number of lines, are the lines parallel, line that acts as a transversal.
• Ask how many angles are there present. List all the angles formed.
• Additional information can be retrieved – no of angles are formed at each point, number of angle pairs, number of linear pairs at each point.
• Talk about supplementary angle pairs – let them identify the supplementary angle pairs for the parallel lines.
• Move the transversal using point D to observe the changes made by the transversal with the parallel lines.
• Children can observe the pair of angles that vary equally
• Mention corresponding angles and their properties
• For a give pair of parallel lines list all the corresponding angles.
• Use point B to show that lines need not be parallel with x-axis to be parallel with each other.
• Inquire about number of parallel lines that can be drawn for a given line.
• Change the position of point D to record other values
 Angle BPD Angle DPQ Total Angle KMP Angle PMN Total Angle ECM Angle MCL Total .
• Evaluation at the end of the activity