Вырожение 4(cos^2t-2sin^2t-2sintcost)

cos t/cost/2+sint/2= cos2*t/cost/2+sint/2=(cost/2+sint/2)(cost/2-sint/2)/cost/2+sint/2=cost/2-sint/2

cos 2t - sin 2t/cos 4t=cos 2t - sin 2t/cos 2*2t=cos 2t - sin 2t/(cos 2t - sin 2t)(cos 2t + sin 2t)=

=1/cos 2t+sin 2t