Răspuns:
Explicație pas cu pas:
[tex]\dfrac{sin(\alpha+\beta)*cos(\alpha-\beta )+cos(\alpha+\beta)*sin(\alpha-\beta )}{cos(\alpha+\beta)*cos(\alpha-\beta )-sin(\alpha+\beta)*sin(\alpha-\beta )} =\dfrac{sin(\alpha+\beta+\alpha -\beta )}{cos(\alpha+\beta+\alpha -\beta )}=\dfrac{sin2\alpha }{cos2\alpha } =\\=tg2\alpha[/tex]
