-π/2 ≦ arcsin(x) ≦ π/2
-1 ≦ x ≦ 1
arcsin(sin(x)) = x (-π/2 ≦ x ≦ π/2)
arcsin(sin(x)) = -x (π/2 ≦ x ≦ 3*π/2)
arcsin(sin(x)) = x - 2*π (3*π/2 ≦ x ≦ 5*π/2)
arcsin(sin(x)) = -x + 3*π (5*π/2 ≦ x ≦ 7*π/2)
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