0,5cos(x/2-π/8)=sin3π/16*cos3π/16
0,5cos(x/2-π/8)=0,5sin3π/4
cos(x/2-π/8)=sinπ/4
cos(x/2-π/8)=√2/2
x/2-π/8=-π/4+2πk U x/2-π/8=π/4+2πk
x/2=-π/8+2πk U x/2=3π/8+2πk
x=-π/4+4πk U x=3π/4+4πk,k∈z
-20π≤-π/4+4πk≤20π
-80≤-1+16k≤80
-79/16≤k≤81/16
k=-4 x=-π/4-16π=-65π/4
k=-3 x=-π/4-12π=-49π/4
k=-2 x=-π/4-8π=-33π/4
k=-1 x=-π/4-4π=-17π/4
k=0 x=-π/4
k=1 x=-π/4+4π=15π/4
k=2 x=-π/4+8π=31π/4
k=3 x=-π/4+12π=47π/4
k=4 x=-π/4+16π=63π/4
k=5 x=-π/4+20π=79π/4
-20π≤3π/4+4πk≤20π
-80≤3+16k≤80
-83≤16k≤77
-83/16≤k≤77/16
k=-5 x=3π/4-20π=-77π/4
k=-4 x=3π/4-16π=-63π/4
k=-3 x=3π/4-12π=-45π/4
k=-2 x=3π/4-8π=-29π/4
k=-1 x=3π/4-4π=-13π/4
k=0 x=3π/4
k=1 x=3π/4+4π=16π/4
k=2 x=3π/4+8π=35π/4
k=3 x=3π/4+12π=5π/4
k=4 x=3π/4+16π=69π/4