cos^2 75 - sin^2 75 = (cos 75)^2 - (sin 75)^2cos 2θ = cos^2 θ - sin^2 θcos 150 = cos(2*75) = cos^2 75 - sin^2 75
cos 150 = cos(180 - 30) = -cos 30 = -√3/2
Ответ: -√3/2
cos^2 75 - sin^2 75 = (cos 75)^2 - (sin 75)^2
cos 2θ = cos^2 θ - sin^2 θ
cos 150 = cos(2*75) = cos^2 75 - sin^2 75
cos 150 = cos(180 - 30) = -cos 30 = -√3/2
Ответ: -√3/2