Applying angle theorems

This lesson develops the concept of using geometric properties to solve problems. Particular attention is paid to interior and exterior angles of polygons.

The lesson starts by considering four regular pentagons arranged so that the ‘gap’ between them is a rhombus. Students must calculate the angles in the rhombus.

The next step is to consider a rhombus where three of the angles are 130 degrees. Students must calculate the two remaining angles.

There are pre-lesson and post-lesson formative assessment tasks. Detailed teacher notes give suggestions on questioning and how to use the resources. Full solutions are given for each of the sections.

This is a concept development lesson from the Mathematics Assessment Resource Service, a collaboration between UC Berkeley and the Shell Centre team at the University of Nottingham. Further information on the collection is given here.

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This resource is part of Mathematics Assessment Resource Service (MARS)