АЯ
Анна Ясинская
sin105=0.9659cos15=0.9659sin15=0.2588cos105=-0.2588
sin 105 = sin (пи/2+15) = cos 15°
sin 105 = sin (пи/2+15°) = - sin 15°
sin105cos15 sin15cos105= - cos²15°·sin²15°·(4/4) =
= (-1/4)·(2·sin 15°·cos 15°)² = (-1/4) sin²(2·15°)=
= (-1/4)sin²30°=(-1/4)·(1/4)= - 1/16
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