# 2. Choose the correct option and justify your choice :  $(ii)\: \frac{1-\tan^{2}45^{o}}{1+ \tan^{2}45^{o}}=$   $(A)\: \tan \: 90^{o}$               $(B)\: 1$            $(C) \: \sin 45^{o}$             $(D) \: 0$

$\frac{1-\tan^{2}45^{o}}{1+ \tan^{2}45^{o}}=$
We know that $\tan 45 = 1$
So, $\frac{1-1}{1+1}=0$