sinx + cos(-x) = 1
sinx + cosx = 1
sinx + sin(π/2 - x) = 1
Transform suma în produs.
2sin(π/4)·cos(π/4 - x) = 1
√2·cos(π/4-x) = 1
cos(π/4-x) = √2 / 2
⇒ π/4 - x = ±arccos(√2 / 2) + 2kπ, k ∈ ℤ
⇒ π/4 - x ±π/4 + 2kπ
⇒ x = π/4 ± π/4 + 2kπ
⇒ x ∈ {π/4 - π/4 + 2kπ; π/4 + π/4 + 2kπ}
⇒ x ∈ {2kπ; π/2 + 2kπ⏐k ∈ ℤ}
