Sin п/12 * sin п/6 *sin 5п/12=
SinП/12 * SinП/6 * Sin5П/6 = SinП/12 * 1/2 * CosП/12 = = 1/2 * 1/2Sin(2 * П/12) = 1/4 * SinП/6 = 1/4 * 1/2 = 1/8