6.2 Equation of a Circle
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Circle as a distance rule

Circle as a distance rule

Coordinate diagram of a circle with centre C(a,b), radius r to a point P(x,y), and a tangent at T meeting the radius at 90 degrees

A circle is the set of all points a fixed distance from a fixed point. The fixed point is the centre and the fixed distance is the radius. In coordinates, a circle with centre (a,b)(a,b)(a,b) and radius rrr has equation:

6.2 Equation of a Circle Lesson

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