Cos113°30 cos 53°30 + sin 113°30 sin 53°30 - вопрос №1133053301133053304467096 от Lidya777 04.09.2020 10:09

Question

Алгебра: Cos113°30 cos 53°30 + sin 113°30 sin 53°30

Lidya777 · Answer

Cos113°30 cos53°30 +sin113°30 sin53°30 =1/2(cos(113°30 +53°30 )+cos(113°30 -53°30 ))+1/2(cos(113°30 -53°30 )-cos(113°30 +53°30 ))=1/2(cos167°+cos60°)+1/2(cos60°-cos167°)=1/2(cos167°+cos60°)-1/2(cos167°+cos60°)=0...

Cos113°30 cos 53°30' + sin 113°30' sin 53°30'