[" A point on "y" -axis is equidistant from "(2,3)" and "(-4,1)" ? "],[" Pree vertices of a parallelogram are "(3,4),(3,8)" and "(9,8)" .Find the fourth vertex."],[" the circumcentre of the triangle whose vertices are "(-2,-3),(-1,0),(7,-6)],[" the circumcentre of the triangle whose vertices are "(-2,-3),(-1,0),(7,-6)],[" the angle subtended at the origin by the line segment whose end points are "(0,10" ."]