Значение косинуса уменьшается с увеличением угла.
2) sin (π/7) = cos((π/2)-(π/7)) = cos(5π/14) = cos(2.5π/7)4) sin (3π/5) = sin (6π/10) = sin ((5π/10)+(π/10)) = cos (π/10) =
= cos (0,5π/5)>cos (π/5).
6) sin (3π/10) = sin (12π/40) = sin ((20π/40)-(8π/40)) =
=cos (8π/40) = cos (1,6π/8) < cos (π/8).