\[ \sqrt {1-x^2} y'(x)-y(x) \sqrt {y(x)^2-1}=0 \] ✓ Mathematica : cpu = 0.14113 (sec), leaf count = 39
\[\left \{\left \{y(x)\to -\sqrt {1+\tan ^2\left (\sin ^{-1}(x)+c_1\right )}\right \},\left \{y(x)\to \sqrt {1+\tan ^2\left (\sin ^{-1}(x)+c_1\right )}\right \}\right \}\] ✓ Maple : cpu = 0.018 (sec), leaf count = 16
\[\left \{c_{1}+\arcsin \left (x \right )+\arctan \left (\frac {1}{\sqrt {y \left (x \right )^{2}-1}}\right ) = 0\right \}\]