JEE Advanced Model Paper 9 with solutions for online practice

Let P be any point on the circle withOP as diameter (O being the origin) the points Q andR are on the same side of the diameter such that ∠POQ = ∠QOR = θ , if P , Q and R be complex numbers z1 , z2 , z3 respectively such that 2√3z22 = (2 + √3) z1z3 , then the value of θ is