= {(cos^2ө-sin^2ө)(cos^2ө+sin^2ө)/cos^2ө}+tan^2ө = 1{(cos^2ө-sin^2ө)/cos^2ө}+tan^2ө =?
{(cos^2ө-sin^2ө)/cos^2ө}+tan^2ө = cos^2ө/cos^2ө - sin^2ө/cos^2ө + tan^2ө = 1 - tan^2ө - tan^2ө = 1
You can ask a new question or answer this question.