4sinx + 2cosx=0

sin5x sinx - cos5x cosx=1/2

cos7x + cos3x=0

1) 2tgx+1=0; 2tgx=-1; tgx=-1/2; x=-arctg0,5+πn

2) - (cos5x cosx-sin5x sinx) = 1/2

-cos (5x+x) = 1/2

cos6x=-1/2

6x = + - (π-π/3) + 2πn

6x = + - (2π/3) + 2πn

x=+-π/9+π/3 * n

3) 2cos ((7x+3x) / 2) * cos ((7x-3x) / 2) = 0

2cos5x cos2x=0

cos5x=0 ili cos2x=0

5x=π/2 + πn 2x=π/2+2πn

x=π/10+π/5 * n x=π/4 + πn