Question

1-2sec^2 theta in terms of sec

Answer 1

1 - 2sec²∅ = 1- sec²∅ - sec²∅
= - ( sec²∅ -1) -sec² ∅

use sec²x - tan² x = 1

= -tan²∅ - sec²∅
= -( tan²∅ + sec²∅)
= -( sin²∅ + 1)/cos²∅

Answer 2

given,

1-2sec^2 x = 1-sec^2 x -sec^2 x

= -(sec^2 x -1) - sec^2 x

= - tan^2 x - sec^2 x

= -(sec^2 x + tan^2 x)