Given x2+y2+siny=4
Differentiating both sides with respect to x, we get
2x+(2y+cosy)dxdy=0
⇒dxdy=2y+cosy−2x
At (−2,0),dxdy=14=4
Also, (2y+cosy)dxdy+2x=0
Again differentiating with respect to x, we get
(2y+cosy)dx2d2y+(2−siny)(dxdy)2+2=0
At (−2,0),dx2d2y+(2−0)(4)2+2=0
⇒dx2d2y=−34