The correct option is
C (12,12) and
1√2Given : The locus of middle point of the chord of the circle x2+y2=1
such that the segment of the chord on the parabola, y=x2−x subtends a right angle at the origin.
⟹hx+ky−1=h2+k2−1⟹hx+ky=h2+k2⟹1=(hx+ky)(h2+k2) −(1)
Equation of parabola, y=x2−x
⟹y(1)=x2−x(1)
⟹y[(hx+ky)(h2+k2)]=x2−x[(hx+ky)(h2+k2)]
⟹hxy+ky2=x2(h2+k2)−hx2+kxy⟹x2(h2+k2−h)+(−k)y2+xy(kh)=0
As parabola, y=x2−x subtends a right angle at the origin.
so, coefficient of x² + coefficient of y²=0
⟹h2+k2−h−k=0
putting h=x,k=y
⟹x2+y2−x−y=0⟹x2−x+14+y2−y+14=12
⟹(x−12)2+(y−12)2=(1√2)²
It is clear that centre of circle is (12,12) and radius of circle is 1√2