question_answer

If \[\sqrt{(1-{{x}^{2}})}+\sqrt{(1-{{y}^{2}})}=a(x-y),\] then \[\frac{dy}{dx}=\]

A)  \[\sqrt{\frac{(1-{{x}^{2}})}{(1-{{y}^{2}})}}\]

B)  \[\sqrt{\frac{(1-{{y}^{2}})}{(1-{{x}^{2}})}}\]

C)  \[\left( \frac{1-{{x}^{2}}}{1-{{y}^{2}}} \right)\]         

D)  \[\left( \frac{1-{{y}^{2}}}{1-{{x}^{2}}} \right)\]