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Circle Theorems
![03132012 Image001](/fileadmin/_processed_/e/f/csm_03132012Image001_d64578fe3e.jpg)
Explore five circle theorems by moving lines and points around the TI-Nspire screen.
Publisher: Texas Instruments UK
Editor: Barrie Galpin
Author: Jay Timotheus
Topic: Mathematics
Tags Circle
Students are able to explore the following circle theorems:
· the angle at the centre is twice the angle at the circumference;
· angles from the same arc in the same segment are equal;
· the angle in a semicircle is a right angle;
· opposite angles in a cyclic quadrilateral add up to 180°;
· the tangent to a circle at a point is perpendicular to the radius
In each case students are encouraged to discover the theorem for themselves before seeing a formal statement . However the activities do not prove the circle theorems. Instead they give students the opportunity to get a sense of how the theorems work, as they move points and lines around and see what happens.
There is .ts file with 14 pages, supported by detailed instructions on a 3-page student handout and teacher notes. The activity forms part of the OxBox, published by Oxford University Press to support their course 'Oxford GCSE Maths'. http://www.oup.com/oxed/secondary/2010gcse/