Let the equation of the circle be ...(i)
Since it passes through (0, 0)
∴ ...(ii)
Since it passes through (4, 0)
∴ ...(iii)
But, from (ii),
∴ From (iii), we have
Since it passes through (0, 3)
∴
∴ From (ii), we have
or
Hence, the equation of circle is:
or
or