oblicz bez tablic matjab9: cos20^o * cos40^o * cos80^o

Bogdan: cos20^o*cos40^o*cos80^o = cos20^o*cos40^o*cos80^o * 1 = cos20^o*cos40^o*cos80^o * (2*2*2*sin20^o / 2*2*2*sin20^o) = 2 * 2sin20^o*cos20^o*cos40^o*cos80^o * (2 / 8sin20^o) = = 2sin40^o * cos40^o*cos80^o * (2 / 8sin20^o) = = 2 * sin80^o*cos80^o * (1 / 8sin20^o) = sin160^o / 8sin20^o = sin20^o / 8sin20^o = 1/8