Cos6x-cos4x=0
-2sin5xsinx=0
sin5x=0⇒5x=πn⇒x=πn/5,n∈z-общее
sinx=0⇒<span>x=πk,k</span>∈z
17а² 34а⁵ 17а² 39в³с²
---------:-------------=------------*-----------=
26в²с³ 39в³с² 26в²с³ 34а⁵
3в
=--------------------= 3в/4а³с=0,75в/а³с
2с 2а³
Sin105° = sin(90° + 15°) = cos15°
sin105°cos15° = cos²15°
cos30° = 2cos²15° - 1
cos²15° = (cos30° + 1)/2 = (√3/2 + 1)/2 = (√3 + 2)/4
Ответ: (√3 + 2)/4
1) cos(x/2-π/12)=0
x/2-π/12=π/2 + πk, k∈Z
x/2=π/12 + π/2 + πk
x/2= π/12 + 6π/12 + πk
x/2 = 7π/12 + πk
x= 2(7π/12 + πk)
x=7π/6 + 2πk, k∈Z
2) sin(x-π/3)+1=0
sin(x-π/3)= -1
x-π/3= -π/2 + 2πn, n∈Z
x=π/3 - π/2 + 2πn
x=2π/6 - 3π/6 + 2πn
x= - π/6 + 2πn, n∈Z
Ответ: 7π/6 + 2πk, k∈Z;
- π/6 + 2πn, n∈Z