ctg 9π/4 = ctg (2.25π)
Так как ctg x = 1/tg x, то ctg (2.25π) = 1/tg (2.25π)
tg (π/4) = 1, поэтому tg (2.25π) = tg (π + π/4) = tg (π/4) = 1
Тогда ctg (2.25π) = 1/1 = 1
Ответ: ctg 9π/4 = 1
ctg 9π/4 = ctg (2.25π)
Так как ctg x = 1/tg x, то ctg (2.25π) = 1/tg (2.25π)
tg (π/4) = 1, поэтому tg (2.25π) = tg (π + π/4) = tg (π/4) = 1
Тогда ctg (2.25π) = 1/1 = 1
Ответ: ctg 9π/4 = 1