Farhan's problem on chords

Two chords meet inside a circle perpendicular to each other. The lengths of the segments of one chord are $x$ and $x+5$ , and those of the other are $x+1$ and $6$ . The distance of the chords' meeting point from the centre of the circle is $\dfrac{\sqrt{a}}{b}$ where a and b are primes. Find the value of $a+b$ .