а) cos a = √(1 - sin^2 a) = √(1 - 0.8^2) = √(1 - 0.64) = √0.36 = 0.6
б) sin 2a = 2 sin a cos a = 2 0.8 0.6 = 0.96
в) cos 2a = cos^2 a - sin^2 a = 0.6^2 - 0.8^2 = 0.36 - 0.64 = -0.28
а) cos a = √(1 - sin^2 a) = √(1 - 0.8^2) = √(1 - 0.64) = √0.36 = 0.6
б) sin 2a = 2 sin a cos a = 2 0.8 0.6 = 0.96
в) cos 2a = cos^2 a - sin^2 a = 0.6^2 - 0.8^2 = 0.36 - 0.64 = -0.28