$$( \sin y ) : \frac { x } { x - y } - \frac { x } { x + y } + \frac { 2 x y } { x ^ { 2 } + y ^ { 2 } }$$
$\frac{x^{4}\sin(y)-y^{4}\sin(y)+\left(xy\right)^{2}+2yx^{3}-x^{4}}{x\left(x+y\right)\left(x^{2}+y^{2}\right)}$
$\frac{y\left(x^{6}\sin(y)+y^{6}\sin(y)+4\left(xy\right)^{3}\sin(y)+3x^{2}y^{4}\sin(y)+3y^{2}x^{4}\sin(y)+2xy^{5}\sin(y)+2yx^{5}\sin(y)+4\left(xy\right)^{3}+x^{2}y^{4}-2y^{2}x^{4}-4yx^{5}-3x^{6}\right)}{\left(x\left(x+y\right)\left(x^{2}+y^{2}\right)\right)^{2}}$
