# Angles associated with parallel lines

From Karnataka Open Educational Resources

Two parallel lines are cut by a transversal the angles formed are alternate angles, corresponding angles co-interior angles and vertically opposite angles.

### Objectives

To understand corresponding angles are equal

To understand alternate angles are equal

### Estimated Time

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-2.ggb”

Download this geogebra file from this link.

### Process (How to do the activity)

- Move the slider to draw a parallel line with the corresponding angles check box unchecked
- How are the two line with each other
- What is the line cutting the two line called
- Bring the slider to initial position : check the corresponding angles check box
- Move the slider to show corresponding angles formed for the two lines
- At the point of intersection of the parallel line and transversal : which other angles are equal
- Is the vertically opposite angle equal to the corresponding angle
- What are alternate angles are they equal
**Evaluation at the end of the activity**

- A minimum of how many corresponding angles should be equal for any two lines to be parallel.
- How many pairs of corresponding angles are formed when a transversal intersects two parallel lines?
- How many pairs of alternate angles are formed when a transversal intersects two parallel lines?