Angabe:

Man löse die exakten Differentialgleichungen!

(cosy + ycosx)dx + (sinx - xsiny)dy = 0

Lösung:

cosy + ycosx = P
sinx - xsiny = Q

dP/dy = -siny + cosx
dQ/dx = cosx - siny

Int...Integral

Int Pdx + Int Q - Int dP/dy dxdy=0

Int cosy + ycosx dx + Int sinx - xsiny - Int cosx - siny dxdy = c
xcosy + ysinx + ysinx + xcosy - ysinx - xcosy = c
ysinx + xcosy = c