cos^2+tan^2=1
the question is supposed to be:
cos^2xtan^2xcos^2x=1
=cos^2x+ (sin^2x/cos^2x)(cos^2x/1)
*the last 2 cos^2x will cancel out leaving you with:
=cos^2x+sin^2x=1
cos^2xtan^2xcos^2x=1
=cos^2x+ (sin^2x/cos^2x)(cos^2x/1)
*the last 2 cos^2x will cancel out leaving you with:
=cos^2x+sin^2x=1