Solve `(xsiny/x)dy=(ysiny/x-x)dx`.

Explanation

`(siny/x)(dy)/(dx) = (y/x.siny/x-1)`
Put `y=vx`
`rArr sinv(v+x(dv)/(dx))=(vsinv-1)`
or `sinv(xdv)/(dx) =-1`
or `intsinvdv=-int(dx)/(x)`
`rArr cosv=log_(e)x+c`
`rArr cosy/x=log_(e )x+c`