Решение
1) cos(π/2) = 1 + cosx
1 + cosx = 0
cosx = - 1
x = π + 2πk, k∈Z
2) tgx - tg(7π/2 - x) = 1
tgx - ctgx = 1
tgx - 1/tgx - 1 = 0
tg²x - tgx - 1 = 0
tgx = z
t² - t - 1 = 0
D= 1 + 4*1*1 = 5
t₁ = (1 - √5)/2
t₂ = (1 + √5)/2
1) tgx = (1 - √5)/2
x₁ = arctg(1 - √5)/2 + πn, n∈Z
2) tgx = (1 + √5)/2
x₂ = arctg(1 + √5)/2 + πm, m∈Z