Key learning points

1. Missing angles can be found using parallel lines.
2. Missing angles can be found using facts about triangles.
3. Missing angles can be found in polygons using knowledge of exterior and interior angles.
4. The relationship between interior and exterior angles can be used to find missing angles.
5. Missing angles can be found by using a combination of all known facts.

Keywords

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

• Alternate angles - 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 lines.

• Interior angles - An interior angle is an angle formed inside a polygon by two of its edges.

• Exterior angle - An exterior angle is an angle on the outside of a polygon between an extension of an edge and its adjacent edge.

Common misconception