Write the product as a sum:

Question

12sin(27x)sin(24x) =

Answer 1

general formula is asinAsinB = (a/2)(cos(A-B)- cos(A+B))

12sin27xsin24x

= (12/2)(cos(27x-24x)-cos(27x+24x))

= 6cos3x -6cos51x

check the answer

12sin27sin24 = about 2.2159

6cos-3 = about 5.992

5cos51 = about 3.776

5.992-3.776 = 2.2159