Преобразуйте данное выражение таким образом, чтобы аргумент соответствующей тригонометрической функции принадлежал промежутку (0; π/2): a) sin(7π/8), cos(-5π/3), tg(0.6π), ctg(-1.2π) б) tg(6π/5), sin(-5π/9), cos(1.8π), ctg(0.9π)

a) sin(7π/8), cos(-5π/3), tg(0.6π), ctg(-1.2π) sin(7π/8) = sin(π - π/8) = sin(π/8) cos(-5π/3) = cos(5π/3) = cos(2π - π/3) = cos(π/3) tg(0.6π) = tg(0.6π - π) = tg(-0.4π) = -tg(0.4π) ctg(-1.2π) = ctg(-1.2π + 2π) = ctg(0.8π) = ctg(0.8π - π) = ctg(-0.2π) = -ctg(0.2π) Результат: sin(π/8), cos(π/3), -tg(0.4π), -ctg(0.2π) б) tg(6π/5), sin(-5π/9), cos(1.8π), ctg(0.9π) tg(6π/5) = tg(π + π/5) = tg(π/5) sin(-5π/9) = -sin(5π/9) = -sin(π - 4π/9) = -sin(4π/9) cos(1.8π) = cos(1.8π - π) = cos(0.8π) = cos(π - 0.2π) = -cos(0.2π) ctg(0.9π) = ctg(0.9π - π) = ctg(-0.1π) = -ctg(0.1π) Результат: tg(π/5), -sin(4π/9), -cos(0.2π), -ctg(0.1π)