Question

sec(x)(sec(x)−cos(x))=

Answer 1

$sec(x)(sec (x) -cos(x)) =1/cos(x)(1/cos(x) - cos(x)) =$

$= 1/cos(x)((1-cos^2(x))/cos(x)) = sin^2(x)/cos^2(x) =$

$= tan^2(x)$

answer: $tan^2(x)$