(sin^2(pi/2+alpha)-cos^2(alpha-pi/2))/(tan^2(pi/2+alpha)-cot^2(alpha-pi/2))sin2(π2+α)−cos2(α−π2)tan2(π2+α)−cot2(α−π2)
=(sin^2(pi/2+alpha)-cos^2(pi/2-alpha))/(tan^2(pi/2+alpha)-cot^2(pi/2-alpha))=sin2(π2+α)−cos2(π2−α)tan2(π2+α)−cot2(π2−α)
=(cos^2(alpha)-sin^2(alpha))/(cot^2(alpha)-tan^2(alpha))=cos2(α)−sin2(α)cot2(α)−tan2(α)
=(cos^2(alpha)-sin^2(alpha))/(cos^2(alpha)/sin^2(alpha)-sin^2(alpha)/cos^2(alpha))=cos2(α)−sin2(α)cos2(α)sin2(α)−sin2(α)cos2(α)
=(cos^2(alpha)-sin^2(alpha))/((cos^4(alpha)-sin^4(alpha))/(sin^2(alpha)cos^2(alpha)))=cos2(α)−sin2(α)cos4(α)−sin4(α)sin2(α)cos2(α)
=(cos^2(alpha)-sin^2(alpha))/(cos^4(alpha)-sin^4(alpha))xx(sin^2(alpha)cos^2(alpha))/1=cos2(α)−sin2(α)cos4(α)−sin4(α)×sin2(α)cos2(α)1
=(cos^2(alpha)-sin^2(alpha))/((cos^2(alpha)-sin^2(alpha))(cos^2(alpha)+sin^2(alpha))xx(sin^2(alpha)cos^2(alpha))/1=cos2(α)−sin2(α)(cos2(α)−sin2(α))(cos2(α)+sin2(α))×sin2(α)cos2(α)1
=sin^2(alpha)cos^2(alpha)=sin2(α)cos2(α)