the sine function is a many-to-one function and therefore has no inverse function.
However if the domain is restricted to -90° ≤ x ≤ 90°
Then the function is one-to-one for this domain
Thus, [tex]sin^{-1}[/tex] x is defined as the angle such that - π/2 ≤ x ≤ π/2
5π/6 is therefore outwith the domain
