| 2tgx | ||
sin2x= | ||
| 1+tg2x |
| 1−tg2x | ||
cos2x= | ||
| 1+tg2x |
| 2t | 1−t2 | |||
3* | −4* | =a | ||
| 1+t2 | 1+t2 |
| 6t−4+4t2 | |
=a | |
| 1+t2 |
| 4 | a | |||
Po obustronnym podzieleniu przez 3: sin2x − | cos2x = | |||
| 3 | 3 |
| 4 | sinα | 3 | |||
= tgα = | ⇒ cosα = | ||||
| 3 | cosα | 5 |
| sinα | a | |||
sin2x − | cos2x = | /*cosα | ||
| cosα | 3 |
| a | 3 | |||
sin2x cosα − sinα cos2x = | * | |||
| 3 | 5 |
| a | ||
sin(2x − α) = | ∊ <−1, 1> | |
| 5 |
| a | ||
−1 ≤ | ≤ 1 /*5 ⇒ −5 ≤ a ≤ 5 | |
| 5 |