Official solution
\[{2^{\sqrt {{{\sin }^2}x - 2\sin x + 5} }} \le {2^{2{{\sin }^2}y}}\]
\[ \Rightarrow \] \[\sqrt {{{\sin }^2}x - 2\sin x + 5} \le 2{\sin ^2}y\]
\[ \Rightarrow \sqrt {{{\left( {\sin x - 1} \right)}^2} + 4} \le 2{\sin ^2}y\]
it is true when sinx = 1, |siny| = 1
so sinx = |siny|