(8 1/3-10 1/2)*12/65=(25/3-21/2)*12/65=(50/6-63/6)*12/65= - 13/6*12/65= - 26/65
- 2 13/65
5,04/36
50,4/36 (0,)
50,4/36 (0,1) (ост. 14)
50,4/36 (144/36) = (0,14)
Ответ: 0,14
Cos2x = sin(x+π/2)
cos²x - six²x = cosx
cos²x-(1-cos²x)-cos x = 0
2cos²x - cos x - 1 = 0, сделаем замену: пусть cos x = t
2t²-t-1 = 0
D = 1+8 = 9
t₁ = (1-3)/4 = -1/2
t₂ = (1+3)/4 = 1
сделаем обратную замену:
cos x = -1/2, х = -4π/3
cos x = 1 x = -2π