2. Alternate angles are equal
3. Allied (co-interior) angles add to 180°
Find the size of angles a and b in the diagram below.
Give a reason for each step in your working.
Vertically opposite angles are equal.
Corresponding angles on parallel lines are equal.
You must write down both of these reasons for full marks.
a
= 64° (Vertically opposite angles are equal)
b = 64° (Corresponding angles on parallel lines are equal)