Cos10*cos50*cos70 равно

Cos 10 cos 50 cos 70

= (1/2) [ 2 cos 50 cos 70 ] cos 10

= (1/2) [ cos 20 + cos 120 ] cos 10

= (1/2) [ cos 20 - - 1 / 2 ] cos 10

= (1/2) cos 20 cos 10 - - [ 1 / 4 ] cos 10

= (1/4) [ 2 cos 20 cos 10 ] - - [ 1 / 4] cos 10

= (1/4) [ cos 30 + cos 10 ] - - (1/4) cos 10

= (1/4) cos 30

= (1/4) sqrt (3) / 2

= sqrt (3) / 8

= 0.2168