sec^2 x
_________________ =
(sec x + 1) (sec x - 1)
sec^2 x
__________ [note tan^2 x + 1 = sec^2x ....so.....sec^2x - 1 = tan^2x ]
sec^2x- 1
sec^2 x
_______
tan^2 x
1 / cos^2 x
_____________
sin^2x / cos^2 x
[ 1 /cos^2 x ] * [ cos^2x / sin^2 x ]
1
_____
sin ^2x
1 1
___ * ____
sinx sin x
cscx * cscx =
csc^2 x