Question

ʃsin 3x sin 6x dx

Answer 1

r u familiar with this formula?
cosc-cosd=2sin(c+d)/2sin(d-c)/2?
here c=A+B and d=A-B

Answer 2

hmmm I'd prefer to use identities. I can't seem find an identity for sin 6x

Answer 3

how about the double angle sin(2x) = 2 sin(x) cos(x)

Answer 4

u can use the one i showed.
cosc-cosd=2sin(d-c)/2sin(c+d)/2
c+d/2=6x
c-d/2=3x
u can find c and d from this

Answer 5

(c+d)/2=6x
(c-d)/2=3x