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The Seven Theorems

Dynamic Geometry & Circle Theorems I've set out these pages so that either you can use them to work out what the theorems are, or you can just go here where they're lurking with suitable diagrams. Geogebra is a free dynamic geometry package, very suitable for illustrating the circle theorems. As it is dynamic geometry, you can move points around and see what happens! Here are GeoGebra Dynamic Worksheet pages with the seven circle theorems (as used in the UK's GCSE Maths exams!!) First circle theorem - angles at the centre and at the circumference. Second circle theorem - angle in a semicircle. Third circle theorem - angles in the same segment. Fourth circle theorem - angles in a cyclic quadlateral. Fifth circle theorem - length of tangents. Sixth circle theorem - angle between circle tangent and radius. Seventh circle theorem - alternate segment theorem. Tim Devereux 11/10/07