Given equation of parabola, y=x2−4x+3 ⇒‌‌(y+1)=x2−4x+4 ⇒‌‌(x−2)2=(y+1) here X=x−2 and Y=y+1,a=‌
1
4
Vertex is (2,−1)=V (say) equation of circle, x2=9−(y−3)2 or (x−0)2+(y−3)2=9 Centre C=(0,3) Now, VC=√(2−0)2+(−1−3)2 =√4+16=√20 =2√5