Locus has always been my problem.Please help.

Let PQ specified by the equation x + y = 3√3 be a chord to the circle x2+y2=27. If the point R moves on the circle, then the locus of centriod of triangle PQR is a circle, the square of whose radius is -

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rocky ·

let r≡(h,k) ,p≡(x1,y1) q≡(x2,y2)

y=3√3-x

put it in circle's equation we get x2=3√3 thus
x1+x2=0

centroid (a,b)=(h/3,6√3+k3)
thus h=3a , k=3b-6√3k

and it lies on circle given , so
put the value of h,k in x2+y2=27

we get radius as 3

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