Key learning points

1. Alternate, corresponding and co-interior angles can be identified in diagrams containing pairs of parallel lines.
2. Facts about angles in parallel lines can be used to find unknown angles.
3. Facts about angles in parallel lines can be used in succession to find multiple unknown angles.

Keywords

• Corresponding angles - Corresponding angles are a pair of angles at different vertices on the same side of a transversal in equivalent positions.

• Alternate angles - Alternate angles are a pair of angles both between or both outside two line segments that are on opposite sides of the transversal that cuts them.

• Co-interior angles - Co-interior angles are on the same side of the transversal line and in between the two other line.

Common misconception