The equation of the parabola is y=x2−6x+12, which can be rewritten as y−3=(x−3)2.
The vertex of the parabola is P(3,3).
The equation of the circle is x2+y2−2x−4y+3=0, which can be rewritten as (x−1)2+(y−2)2=2.
The center of the circle is C(1,2) and its radius is r=2.
The distance between the point P and the center C is:
PC=(3−1)2+(3−2)2=4+1=5
Since PC=5>r=2, the point P lies outside the circle.
Let the line through P intersect the circle at R and S, and let M be the midpoint of the chord RS. The perpendicular distance from the center C to the chord is CM.
Using the right-angled triangle △PCM, the distance from P to the midpoint M is PM=PC2−CM2.
The lengths of the segments are PR=PM−RM and PS=PM+RM.
Therefore, the sum of the distances is:
PR+PS=(PM−RM)+(PM+RM)=2PM=2PC2−CM2
To maximize (PR+PS)2, we need to maximize PC2−CM2. This occurs when CM is minimized, which means CM=0. This happens when the line passes through the center C of the circle.
Substituting CM=0, we get the maximum sum:
PR+PS=2PC=25
Thus, the maximum value of (PR+PS)2 is:
(25)2=4×5=20
Answer: 20