General solution of substitution of high number variables ~ photos ~

Let u=x+y, then the equation becomes xdu/dx+sinu=0. Separate variables, du/sinu =-dx/X. Two-sided integration, ln(cscu-cotu)=-lnx+lnC, so x * (cscu-cotu) = C. The general solution of the original differential equation is x * (CSC (x+y)-cot (x+y)) = C.

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