I need to prove this identity, any idea on how I do it?

${\mathrm{sin}}^{2}\alpha -{\mathrm{cos}}^{2}\beta ={\mathrm{sin}}^{2}\beta -{\mathrm{cos}}^{2}\alpha $

${\mathrm{sin}}^{2}\alpha -{\mathrm{cos}}^{2}\beta ={\mathrm{sin}}^{2}\beta -{\mathrm{cos}}^{2}\alpha $