(cos^4ө- sin^4ө/ cos^2ө)+ tan^2ө

Question

= {(cos^2ө-sin^2ө)(cos^2ө+sin^2ө)/cos^2ө}+tan^2ө
= 1{(cos^2ө-sin^2ө)/cos^2ө}+tan^2ө
=?

Answer 1

from your line
{(cos^2ө-sin^2ө)/cos^2ө}+tan^2ө
= cos^2ө/cos^2ө - sin^2ө/cos^2ө + tan^2ө
= 1 - tan^2ө - tan^2ө
= 1