Tangents are drawn from a point on the circle x2+y2−4x+6y−37=0     to the circle   x2+y2−4x+6y−12=0The angle between the tangents, is

the equations of the circles are:  (x−2)2+(y+3)2=(52)2                            .......(i)and (x−2)2+(y+3)2=52                                (ii)Clearly, (i) is the direction circle of (ii). So, required angle is π2