Find the equation of the circle which passes through the points (2, 3) and (4, 5) and the centre lies on the straight line y – 4x + 3 = 0.
Let the centre of the circle be C(h,k)
Given that the centre lies on the line y-4x+3=0
y-4x+3=0
k-4h+3=0
k=4h-3
AC2=BC2
(h-2)2+(4h-3-3)2=(h-4)2+(4h-3-5)2
h2-4h+4+16h2-48h+36=h2-8h+16+16h2-64h+64
20h=40
h=2
k=4h-3=5
radius=
Therefore equation of the circle is : (x-2)2+(y-5)2=4
x2+y2-4x-10y+25=0