Learn how to apply formulae for the interior and exterior angles of a polygon and how to create tiling patterns and tessellations with this GCSE guide.

Learn about and revise angles, lines and multi-sided shapes and their properties with this BBC Bitesize GCSE Maths Edexcel study guide.

There are specific rules for calculating in either direction. To calculate azimuths clockwise around a traverse: Subtract the interior angle from the back azimuth of the preceding line.