Angles made by parallel lines
Parallel lines are straight lines which have the same direction and so never meet. Arrowheads show lines are parallel.
A straight line that cuts a pair of parallel lines is called an intersecting transversal.
When a pair of parallel lines meet an intersecting transversal, pairs of angles with particular properties are made.
Corresponding angles
Corresponding angles are equal. The lines make an F shape. Notice that the F shape can be upside down or back to front.
Alternate angles
Alternate angles are equal. The lines make a Z shape which can also be back to front.
Vertically opposite angles
We've already seen that intersecting lines create vertically opposite angles that are equal. The lines make an X shape.
Co-interior angles
Co-interior angles add up to 180°. The lines make a C shape which can also be back to front.
