Answer:
  θ  = 45º
Explanation:
The light that falls on the second polarized is polarized, therefore it is governed by the law of Maluz
       I = I₀ cos² θ
in the problem they ask us
      I = ½ I₀
let's look for the angles
       ½ I₀ = I₀ cos² θ
       cos θ  = √ ½ = 0.707
      θ  = cos 0.707
      θ  = 45º