Question

cos^2(θ)(1+tan^2(θ))=1
I need to prove this:
so far I got that tanx=sinx/cosx:
cos^2(θ)(1+sin^2(θ)/cos^2(θ))
But I am not sure if that is correct

Answer 1

= ( 1/ sec²θ ) * sec²θ = 1

Answer 2

1+tan^2 = sec^2 = 1/cos^2

Answer 3

sin^2 + cos^2 = 1

sin^2 + cos^2 = 1
---------------- = tan^2 + 1 = sec^2
cos^2

Answer 4

you can also multiply the left side out to get cos^2x + sin^2x.... = 1