Angles associated with parallel lines

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


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