$\frac{\cos(2A)-\cos(90)}{\cos(2A)+\cos(90)}$

$\frac{\sin(2A)\left(\left(\sin(45)\sin(A)\right)^{2}+\left(\sin(45)\cos(A)\right)^{2}-\left(\cos(45)\sin(A)\right)^{2}-\left(\cos(45)\cos(A)\right)^{2}\right)}{\left(\left(\cos(45)\cos(A)\right)^{2}-\left(\sin(45)\sin(A)\right)^{2}\right)^{2}}$