SIN(x + pi/4)^2 > 1/2
SIN(x + pi/4) = SIN(x)·COS(pi/4) + SIN(pi/4)·COS(x)
SIN(x + pi/4) = √2·COS(x)/2 + √2·SIN(x)/2
(√2·COS(x)/2 + √2·SIN(x)/2)^2 > 1/2
SIN(x)·COS(x) + 1/2 > 1/2
SIN(x)·COS(x) > 0
1/2·SIN(2·x) > 0
SIN(α) > 0
0 + 2·k·pi < α < pi + 2·k·pi
0 + 2·k·pi < 2·x < pi + 2·k·pi
k·pi < x < k·pi + pi/2