1.
dy=[sec(x+y)]^2*d(x+y)
[cos(x+y)]^2*dy=dx+dy
-[sin(x+y)]^2*dy=dx
dy=-[csc(x+y)]^2*dx
2.
d(y^2)=d(x+lny)
2ydy=dx+dy/y
(2y-1/y)dy=dx
dy=ydx/(2y^2-1)