Consider the circle `x^2 + y^2 = 9` and the parabola `y^2 = 8x.` They intersect at P and Q in the first and the fourth quadrants, respectively. Tangents to the circle at P and Q intersect the x-axis at R and tangents to the parabola at P and Q intersect the x-axis at S.
The radius of the incircle of the triangle PQR is
4
3
`8/3`
2