B6. sin^2(x/2) - 5sin(x/2) + 4 = 0
D= 25 - 16= 9
= 3
- не подходит, т.к. sin(x/2) лежит в [-1;1]
sin(x/2) = 1 => sin(x/2) = pi/2 + 2pi*n => x = pi + 4pi*n
Ответ: pi + 4pi*n, где n - целое
B8.
cos28 = cos(90-62) = sin62
cos34 = cos(90-56) = sin56
3cos28*cos34 - 3cos62cos56 = 3sin62sin56 - 3cos62cos56 = -3(cos62cos56 - sin62sin56) = -3cos(62+56) = -3cos118 = -3cos(90+28) = -3*(-sin28) = 3sin28
sin74 = sin(90-16) = cos16
cos46 = cos(90-44)=sin44
sin74*cos46 - cos44*sin16 = sin44*cos16 - cos44*sin16 = sin(44-16) = sin28
В итоге получается:
3sin28/sin28 = 3
Ответ: 3
D= 25 - 16= 9
sin(x/2) = 1 => sin(x/2) = pi/2 + 2pi*n => x = pi + 4pi*n
Ответ: pi + 4pi*n, где n - целое
B8.
cos28 = cos(90-62) = sin62
cos34 = cos(90-56) = sin56
3cos28*cos34 - 3cos62cos56 = 3sin62sin56 - 3cos62cos56 = -3(cos62cos56 - sin62sin56) = -3cos(62+56) = -3cos118 = -3cos(90+28) = -3*(-sin28) = 3sin28
sin74 = sin(90-16) = cos16
cos46 = cos(90-44)=sin44
sin74*cos46 - cos44*sin16 = sin44*cos16 - cos44*sin16 = sin(44-16) = sin28
В итоге получается:
3sin28/sin28 = 3
Ответ: 3