Question

cos4A*cosA+sin4A*sinA / sin3A помогите плиз

Answer 1

$\frac{cos(4 \alpha )*cos \alpha +sin(4 \alpha )*sin \alpha }{sin(3 \alpha )}= \frac{cos(4 \alpha - \alpha )}{sin(3 \alpha )}= \frac{cos(3 \alpha )}{sin(3 \alpha )}=ctg(3 \alpha )$