Пошаговое объяснение:
0<=πk/2<=4π
0<=k/2<=4
0<=k<=8
k=0 x=0
k=1 x=π/2
k=2 x=π
k=3 x=3π/2
k=4 x=2π
k=5 x=5π/2
k=6 x=3π
k=7 x=7π/2
k=8 x=4π
