0≤y≤π20 \leq y \leq \frac{\pi}{2}0≤y≤2π
0<y≤π20<y \leq \frac{\pi}{2}0<y≤2π
−π2≤y<0\frac{-\pi}{2} \leq y<02−π≤y<0
π2<y≤π\frac{\pi}{2}<y \leq \pi2π<y≤π