sin2xsin2x+cos2xsin2x=1sin2x1+cot2x=csc2x \ dfrac {\ sin x (\ csc x-\ sin x)} {1-\ sin x} &=\ dfrac {\ ...sin2xsin2x+cos2xsin2x=1sin2x1+cot2x=csc2x \ dfrac {\ sin x (\ csc x-\ sin x)} {1-\ sin x} &=\ dfrac {\ sin x\ cdot\ csc x-\ sin ^ {2} x} {1-\ sin x}\\\ (sec2x)(1−sin2x)−(sinxcscx+cosxsecx)=sec2x⋅cos2x−(sin2x+cos2x)=1−1=0