x(x-y)(dy)/(dx)=y(x+y)

Which of the following is not the differential equation of family of curves whose tangent form an angle of (pi)/(4) with the hyperbola xy=c^(2)?(a)(dy)/(dx)=(x-y)/(x+y)(b)(dy)/(dx)=(x)/(x-y)(c)(dy)/(dx)=(x+y)/(x-y) (d)N.O.T.

Which of the following is not the differential equation of family of curves whose tangent form an angle of pi/4 with the hyperbola xy= c^2 ? (a) dy/dx=(x-y)/(x+y) (b)dy/dx=(x)/(x-y) (c)dy/dx=(x+y)/(x-y) (d)N.O.T.

The solution of the differential equation x cos((y)/(x))(dy)/(dx)=y cos((y)/(x))+x is

Solve : x " sin"(y)/(x).(dy)/(dx)=y " sin"(y)/(x)-x