а) sin210°sin465°cos465°cos539° = sin(465°-210°)cos(465°+539°) = sin255°cos1004° = -sin(105°)cos(164°) = -sin(105°)cos(16°) = -sin105°cos16° = -0.9781 * 0.9613 ≈ -0.9399

б) cos375°sin231°tg410°ctg609° = cos(375°+231°)tg410°ctg(609°) = cos606°tg410°ctg609° = cos(606°-410°)ctg(609°) = cos196°ctg(609°) = cos(196°) cot(609°) = cos(196°) tan(609°) = cos(196°) sin(609°) / cos(609°) = cos(196°)sin(609°)/cos(609°) = cos(196°)tan(609°) = cos(196°) tg(609°) = cos196° tg(609°) = cos(196°) cotg(609°) = cos(196°) coth(609°) = cos(196°) 1/tan(609°) = cos(196°) / tan(609°) = cos(196°) / sin(609°) = cos(196°) / sin(609°) = 0.9612 / 0.9239 ≈ 1.0414