Conic Sections

Let P be the point on the parabola y = x2 such that the slope of the tangent to the parabola at the point P is 4 . Let Q be the point in the first quadrant lying on the circle x2 + y2 = 2 such that the slope of the tangent to the circle at the point Q is -1 . Let R be the point in the first quadrant lying on the ellipse x2 + 4y2 = 8 such that the slope of the tangent to the ellipse at the point R is - 12 . Then the radius of the circle passing through the points P, Q and R is

1. 10
2. 5
3. 52
4. 2 5