Lesson 2: Transversals - Interior Supplementary and Exterior Supplementary Angles

   Constructing Knowledge

Interior angles on the same side of a transversal crossing two parallel lines are supplementary (their measures will add to 180°). Exterior angles on the same side of a transversal crossing two parallel lines are also supplementary.



The sets of interior supplementary angles are inside the parallel lines:

  • ∠D and ∠E are on the left side of the transversal and add to 180°.

  • ∠B and ∠G are on the right side of the transversal and add to 180°.

The sets of exterior supplementary angles are outside the parallel lines:

  • ∠A and ∠H are on the left side of the transversal and add to 180°.

  • ∠C and ∠F are on the right side of the transversal and add to 180°.

   Multimedia

A video describing interior and exterior supplementary angles is provided.



EXAMPLE

Name the interior supplementary angles and exterior supplementary angles in the aerial photograph of the group of airport runways shown.

Solution


The sets of interior supplementary angles are:

  • ∠4 and ∠6
  • ∠2 and ∠5

The sets of exterior supplementary angles are:

  • ∠1 and ∠7
  • ∠3 and ∠8


Now, it is your turn! Complete the questions in your Chapter 6, Lesson 2 Practice Makes Perfect that refer to Interior Supplementary and Exterior Supplementary Angles.



2014 © Alberta Distance Learning Centre