29)find the centroid of the circle whose vertices are (4,-8),(-9,7),(8,13).
30)if the area of triangle PQR,where P(2,1),Q(x,1) and R(2,y) is 6 sq units ,then find the relationship between x and y.
31)the centre of a circle is (x+2,x-1) .Find x if the circle passes through (2,-2) and(8,-2).
32)if P(9a-2,-b) divides the line segment joining A(3a+1,-3) and B(8a,5) in the ratio 3:1 . Find the value of a and b.