Nach \(x\) umstellen liefert:
\(x=\sqrt{\cos^2(y)+1}\), also
\(\frac{dx}{dy}=\frac{1}{2\sqrt{\cos^2(x)+1}}\cdot 2\cos(y)(-\sin(y))=\)
\(=-\frac{\cos(y)\sin(y)}{x}=-\frac{\sqrt{x^2-1}\sqrt{1-\cos^2(y)}}{x}=-\frac{\sqrt{-x^4+3x-2}}{x}\),
also
\(f'(x)=-\frac{x}{\sqrt{-x^4+3x^2-2}}\)