In this section, we will investigate one final pair of angles formed when two parallel lines are intersected by another line (known as a transversal). [br][br]the below applet shows examples of [i]co-interior angles.[/i]
Use the above applet to investigate co-interior angles. [br]In your own words, describe what [i]co-interior[/i] angles are.
Co-interior angles on parallel lines are on the same side of a transversal line and between the parallel lines.
What do co-interior angles add up to?
[math]180^\circ[/math]
PART 1
For each diagram below, decide whether the angles marked are co-interior angles or not.
Which of the above diagrams show co-interior angles?
PART 2
Consider the below diagram.
What is the missing marked angle? [b]Justify your answer.[/b]
The marked missing angle is 76°.[br][br]By vertically opposite angles, the co-interior angle to the marked angle is 104°. [br]Hence, the missing angle is 180°-104°=76°, since co-interior angles add to 180°.