Coordinate Geometry - Finding the Centre and Radius of a Circle

Coordinate Geometry - Finding the Centre and Radius of a Circle

The points \(A(7,-6)\), \(B\left( 9,2 \right)\) and \(C\left( 1,4 \right)\) lie on a circle as shown in the diagram.

  1. Find the gradients of \(AB\) and \(BC\) and show that \(AC\) is the diameter of the circle.
  2. Find the coordinates of the centre of the circle and find the radius of the circle.
  3. Find the equation of the circle.
  4. Find the equation of the perpendicular bisector of \(BC\) and determine whether it passes through the centre of the circle.

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Answer:(a) \(m_{AB}=4\), \(m_{BC}=-\frac14\), so \(AC\) is the diameter (b) Centre \((4,-1)\), radius \(\sqrt{34}\) (c) \((x-4)^2+(y+1)^2=34\) (d) \(y=4x-17\), which passes through the centre

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