| sinx | ||
| | | ≥ sinx + 2, | |
| cosx |
| 2sin(x/2)cos(x/2) | 2sin(x/2)cos(x/2) | |||
| | | ≥ | +2 | ||
| cos2(x/2)−sin2(x/2) | cos2(x/2)+sin2(x/2) |
| 2tg(x/2) | 2tg(x/2) | |||
| | | ≥ | + 2 | ||
| 1−tg2(x/2) | 1+tg2(x/2) |
| t | t | |||
| | | ≥ | +1 | ||
| 1−t2 | 1+t2 |