Let the intensity of light from the first polaroid is I_o
The intensity through the second polaroid is,

where,

For the angle,

The intensity of light from the second polaroid is,
![\begin{gathered} I=I_o\cos ^2(45^(\circ)) \\ I=I_(\circ)(\frac{1}{\sqrt[]{2}})^2 \\ I=(I_(\circ))/(2) \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/itud1r0hy7qca4jolbe5dcbpnzj7a6j0eq.png)
Thus, the intensity of light from the second polaroid becomes half if the angle between the direction of polarization of two polaroids is 45 degree.