Question

sin4a - sin3a + cos3,5a

Answer 1

$\displaystyle\bf\\Sin4\alpha -Sin3\alpha +Cos3,5\alpha =\\\\=2Sin\frac{4\alpha -3\alpha }{2} Cos\frac{4\alpha +3\alpha }{2}+Cos3,5\alpha = \\\\=2Sin0,5\alpha Cos3,5\alpha +Cos3,5\alpha =\\\\=Cos3,5\alpha \cdot(2Sin0,5\alpha +1)$