Given: Equation of parabola is y2=4x and the equation of circle is x2+y2−4x−16y+64=0.
We know that, equation of normal to parabola is given by, y=mx−2m−m3.
Also, the centre of given circle is (2,8).
The normal of parabola is passing through center of circle.
⇒8=2m−2m−m3
⇒m=−2
So point P on parabola is given by,
(am2,−2am)=(4,4)
And C=(2,8)
⇒PC=4+16=20
d2=20.