ctg(arccos(-1)) = ctg(π) = 0
arctg(1) = π/4
Therefore, ctg(arccos(-1) + arctg(1)) = ctg(0 + π/4) = ctg(π/4) = 1
ctg(arccos(-1)) = ctg(π) = 0
arctg(1) = π/4
Therefore, ctg(arccos(-1) + arctg(1)) = ctg(0 + π/4) = ctg(π/4) = 1