\[ \sqrt {1-x^2} y'(x)-y(x) \sqrt {y(x)^2-1}=0 \] ✓ Mathematica : cpu = 0.135985 (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 = 0.024 (sec), leaf count = 16
\[\arcsin \relax (x )+\arctan \left (\frac {1}{\sqrt {y \relax (x )^{2}-1}}\right )+c_{1} = 0\]