№30
1. 0+π/2=π/2
2. π/3+π/6=2π/6+π/6=3π/6=π/2
3. 0+π/6=π/6
4. π/4+π/3=3π/12+4π/12=7π/12
5. -π/6+π/6=0
6.-π/6+2π/3=4π/6-π/6=3π/6=π/2
7. 3π/4-π/2=3π/4-2π/4=π/4
8. -π/3+5π/6=3π/6=π/2
9.π/4-π/3=-π/12
10. π/2+0=π/2
31.
-π/6<π/6 π/3=π/3<br>π/3<π/2 2π/3>π/4