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Question
`(1+ tan^2 theta)/(1+ tan^2 theta)= (cos^2 theta - sin^2 theta)`
Solution
LHS = `(1- tan^2 theta)/(1+ tan^2 theta)`
=`(1-(sin^2 theta)/(cos^2 theta))/(1+(sin^2 theta)/(cos^2 theta))`
=`(cos^2 theta- sin^2 theta)/(cos^2 theta+ sin ^2 theta)`
=`(cos^2 theta+sin^2 theta)/1`
=`cos^2 theta- sin^2 theta`
= RHS
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