Polarized light of intensity I0 is incident on a pair of polarizing sheets. Let 1 and 2

Polarized light of intensity I0 is incident on a pair of polarizing sheets. Let θ1 and θ2 be the angles between the direction of polarization of the incident light and the transmission axes of the first and second sheets, respectively. Show that the intensity of the transmitted light is I = I0 cos2 θ1 cos2 (θ1 − θ2).