[填空题]
Two Polaroids are aligned so that mxp k39rti n*ov*d 2y0twj+5xthe light pa (25jt 8sqc gp.+n3 e8s5zud bu a;g*(laxfzbrssing through them is a maximum. At what angle should one of them be placed so that thp u8js5g(8lbzc3; f2+dntab. r5gx sq ua (z*ee intensity is subsequently reduced by half? $^{\circ}\,$
