Three polarizing disks whose planes are parallel and centered on common axis. The directions of their transmission

axes relative to the vertical are respectively: ${}_1=18,{}_2=36,$ and ${}_3=55.$ A beam of light polarized along the

vertical is incident onto the first polarizer with an intensity of $I_0=20\frac{W}{m^2}.$ Calculate the transmitted intensity through

all three polarizers.

$\frac{W}{m^2}$