Нужно решить 3 примера Решить
1. ctg(-п/3) tg(п/3) + sin п/2 * cos 5п/6
2.ctg 225-sin 210+cos135
3. 1-cos^2t/1-sin^2t+tgt* ctgt
Спасибо

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вопрос

ctg(-π/3) = -1/tg(π/3) = -1/(√3) = -√3, tg(π/3) = √3, sin(π/2) = 1, cos(5π/6) = -√3/2

Итак, ctg(-π/3) tg(π/3) + sin(π/2) cos(5π/6) = -√3 √3 + 1 (-√3/2) = -3 - √3/2 = - 3.5

ctg(225) = -1/tg(225) = -1/(tan(225)) = -1/(tan(225-180)) = -1/tan(45) = -1/1 = -1
sin(210) = sin(210-180) = sin(30) = 1/2
cos(135) = cos(135-90) = -√2/2

Итак, ctg(225) - sin(210) + cos(135) = -1 - 1/2 - √2/2 = -1 - 1/2 - √2/2 = -3/2 - √2/2

(1-cos^2(t))/(1-sin^2(t)) + tg(t) ctg(t) = (sin^2(t))/(cos^2(t)) + tg(t) ctg(t) = (sin^2(t))/(cos^2(t)) + 1 = (sin^2(t) + cos^2(t))/(cos^2(t)) = 1/(cos^2(t)) = sec^2(t)