Verified answer

1 - 2 sin^2 nθ = cos^2 nθ + sin^2 nθ - 2 sin^2 nθ

....................= cos^2 nθ - sin^2 nθ

....................= cos 2nθ

here n= 2

then

1 - 2 sin^2 2θ = cos 2 * 2 θ = cos 4θ

is the question 1-2sin^2 2θ if it is ten i think d cause cos2a = 1-2sin^2 a

sin²(2t) = (1 - cos(4t))/2

1 - 2*sin²(2t) = 1 - (1 - cos(4t)) = cos(4t)

D