Except for third party materials and otherwise stated below, this content is made available under a Creative Commons Attribution-ShareAlike licence (). The material acknowledged below is Proprietary and used under licence for this project, and not subject to the Creative Commons Licence. This means that this material may only be used unadapted within the TESS-India project and not in any subsequent OER versions. This includes the use of the TESS-India, OU and UKAID logos.
Grateful acknowledgement is made to the following sources for permission to reproduce the material in this unit:
Figure 2: © unknown
Figure 4: adapted from https://commons.wikimedia.org/ wiki/ File:Thales%27_Theorem_Tangents.svg.
Every effort has been made to contact copyright owners. If any have been inadvertently overlooked the publishers will be pleased to make the necessary arrangements at the first opportunity.
Video (including video stills): thanks are extended to the teacher educators, headteachers, teachers and students across India who worked with The Open University in the productions.