The locus of the mid points of the chords of the circle C1:(x−4)2+(y−5)2=4 which subtend an angle θ1 at the centre of the circle C1 , is a circle of radius r1 . If θ1=3π , θ3=32π and r12=r22+r32 , then θ2 is equal to
(1) 4π
(2) 43π
(3) 6π
(4) 2π