Question

Prove that sin5a cos3a + cos5a sin3a = sin9a cos a - cos9a sina

Answer 1

Answer:

sin(5a+3a)

sin(8a)

sin(9a-a) (add and subtract a) and

sin9a cosa - cos9a sina

Explanation:

by using identity

sin(a+b)=sina cosb + cosa sinb

and

sin(a-b)=sina cosb -cosa sinb