Question

sin2ß - tgß – cos2ß tgß срочноооооо​

Answer 1

$sin2 \beta - tg \beta - cos2 \beta tg \beta = \\ = sin2 \beta - tg \beta (1 + cos2 \beta ) = \\ = 2sin \beta cos \beta - \frac{sin \beta }{cos \beta } ( {sin}^{2} \beta + {cos}^{2} \beta + {cos}^{2} \beta - {sin}^{2} \beta ) = \\ = 2sin \beta cos \beta - \frac{sin \beta }{cos \beta } \times 2 {cos}^{2} \beta = \\ = 2sin \beta cos \beta - 2sin \beta cos \beta = 0$