Cos( α+ π) + sin ( α- 3π/2) - ctg( π/2 + α)*tg( 3π/2 + α)=? sin 420+ cos(-390) + tg(-1230) - ctg420=? sin 5π /18*cos π /9 - sin π/9 * cos 5 π/ 18 =? tg² α + sin²α - 1/ cos²α=?
Cos( α+ π) + sin ( α- 3π/2) - ctg( π/2 + α)*tg( 3π/2 + α)=? sin 420+ cos(-390) + tg(-1230) - ctg420=? sin 5π /18*cos π /9 - sin π/9 * cos 5 π/ 18 =? tg² α + sin²α - 1/ cos²α=?
Гость
Ответ(ы) на вопрос:
Гость1) ... = -cos a + cos a + tg a*(-ctg a)= - ctg a*tg a = -1
2) .... = sin 60 - cos 30 - tg 150 - ctg 60 = sin 60 - cos 30 - tg (180 - 30) - ctg 60 = kor3/2 - kor3/2 + kor3/3 - kor3/3 = 0
Гость = -cos a + cos a + tg a*(-ctg a)= - ctg a*tg a = -1
= sin 60 - cos 30 - tg 150 - ctg 60 = sin 60 - cos 30 - tg (180 - 30) - ctg 60 = kor3/2 - kor3/2 + kor3/3 - kor3/3 = 0
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