Q14 of 62 Page 11

Find the equation of a circle with centre (2,2) and passes through the point (4,5).


Since the centre is (2, 2)

We have (x – 2)2 + (y – 2)2 = r2

This circle passes through the point (4, 5)

(4 – 2)2 + (5 – 2)2 = r2

or 4 + 9 = r2

or r2 = 13

The required equation of the circle is

(x – 2)2 + (y – 2)2 = 13

or x2 – 4x + 4 + y2 – 4y + 4 = 13

or ; x2 + y2 – 4x – 4y - 5 = 0.

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