Asked by Anon
(1-tanx^2)/(1+tanx^2)=cos(2x)
Answers
oobleck
(1-tanx^2)/(1+tanx^2)
[(cos^2x - sin^2x)/cos^2x ] /sec^2x
cos^2x - sin^2x
cos2x
QED
[(cos^2x - sin^2x)/cos^2x ] /sec^2x
cos^2x - sin^2x
cos2x
QED