Two variable chords AB and BC of a circle x2+y2=a2 are such that AB = BC = a. M and N are the midpoints of AB and BC, respectively, such that the line joining MN intersects the circles at P and Q, where P is closer to AB and O is the center of the circle.∠OAB is The angle between the tangents at A and C isThe locus of the point of intersection of tangents at A and C is