\[ \sqrt {1-x^2} y'(x)-y(x) \sqrt {y(x)^2-1}=0 \] ✓ Mathematica : cpu = 0.113162 (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 = 0.016 (sec), leaf count = 16
\[ \left \{ \arcsin \left ( x \right ) +\arctan \left ( {\frac {1}{\sqrt { \left ( y \left ( x \right ) \right ) ^{2}-1}}} \right ) +{\it \_C1}=0 \right \} \]