1)cos(4x/3-3π/4)=√2/2
4x/3-3π/4=±π/4+2πk
4x/3=3π/4±π/4+2πk ;•3/4
x=9π/16±3π/16+3πk/2
x1=9π/16+3π/16+3πk/2=11π/16+3πk/2
x2=9π/16-3π/16+3πk/2=3π/8+3πk/2
2)-2π≤11π/16+3πk/2<2π<br>-32π≤11π+24πk<32π<br>-43π≤24πk<21π<br>-43/24≤k<21/24<br>-43/24≤k<7/8<br>-1 19/24≤k<7/8<br>k={-1;0}
2)-2π≤3π/8+3πk/2<2π<br>-16π≤3π+12πk<16π<br>-19π≤12πk<13π<br>-19/12≤k<13/12<br>k={-1;0;1}