Show what you have discovered by completing these tasks:
Alternate and corresponding angles are only equal if the lines are parallel. Co-interior angles are only supplementary if the lines are parallel.
On this interactive page1, you can click on the check box to hide the illusion. Use the protractor the measure the corresponding angles. Drag one of the blue circles to rotate the protractor. Are the lines parallel?
Take this quiz2 to test your knowledge of angles. Work with a partner and make sure that you state the geometric reasons for each answer. There are many possible geometric reasons:
alternate angles on parallel lines
co-interior angles on parallel lines
corresponding angles on parallel lines
adjacent angles
Some questions involve more than one reason and usually these questions can be solved in more than one way.
Find a question in the quiz that has more than one method of solution.
Take a screenshot of the diagram and paste it into Microsoft OneNote5, or any software of your choice.
Include mathematical working showing two ways of finding the answer, giving geometric reasons for each.
© State of NSW, Department of Education, 2018