Упростите: (cos6a-cos4a)÷sin5a a-альфа

Question

Упростите:
(cos6a-cos4a)÷sin5a


a-альфа

Answer 1

Cos6a-cos4a=-2sin((α+β)/2)*sin((α-β)/2)=-2sin5a*sina
-2sin5a*sina/sin5a=-2sina