Find the equation of a circle with centre (2,2) and passes through the point (4,5).
The centre of the circle is given as (h,k) = (2,2).
Since, the circle passes through point (4,5), the radius (r) of the circle is the distance between the points (2,2) and (4,5).
r = 
=
=
=
Thus, the equation of the circle is
(x– h)2+ (y – k)2 =r2
(x –h)2 + (y – k)2 = 
x2 - 4x+4 +y2- 4y+4 =13
x2 +y2 – 4x -4y – 5= 0
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