Answer:
73.5°
Explanation:
I = I₀ Cos²Ф.
.92 = Cos²Ф
Ф = 16.5°
So first sheet makes an angle of 16.5° with the vertical.
Second sheet must be perpendicular to the first one because it blocks the whole light. So second sheet makes an angle of 90 + 16.5 = 106.5° with the vertical.That is 73.5 ° with the vertical. Or it may form an angle of 90-16.5 =
73.5° with the vertical when we consider in counter-clockwise direction.