These resources from the CMEP web site explore the properties of triangles and circles using coordinate geometry. Have a go at proving some geometrical connections, and prove Pythagoras's theorem in an intriguing way you may not have seen before!
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The quintessential proof
In this resource, the aim is to understand a fundamental proof of Pythagoras's Theorem.
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Quadrature of the lunes
A lune is the area left when part of a circle is cut off by another circle. Can you work out the area?
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Finding circles
Can you find the centre and equation of a circle given a number of points on the circle? When is it possible and when is it not?
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The circle of Apollonius... coordinate edition
Can you sketch and then find an equation for the locus of a point based on its distance from two fixed points?