1Explain why vertically opposite angles are equal, without measuring anything.
2What is the difference between complementary and supplementary angles?
3Two parallel lines are cut by a transversal and one angle is 72°. Find all eight angles and give a reason for each kind.
4A diagram shows two lines cut by a transversal but no arrow marks. What can and cannot be concluded?
5Why does the whole eight angle picture only contain two different sizes?