The circle passes through the origin and makes intercepts a with x-axis and b with y-axis.
OA = a, OB = b
∴ The co-ordinates of A are (a, 0) and of B are (0, b)
Now, we have to find the equation of a circle which passes through the points O (0, 0), A (a, 0), B (0, b).
Let the equation of the circle
...(i)
Since it passes through (0, 0)
∴
...(ii)
Since it passes through A (a, 0)
∴
...(iii)
But, from (ii),
∴ from (iii), we have
Since the circle passes through (0, b)
∴
∴ from (ii), we have
∴ The equation of circle is:
or
Hence, the equation of circle is :