To evaluate the integral (sin(x)^5)*(cos(x)^4) use:

a)product-to-sum identities
b) half-angle identities
c) integration by parts
d) the substitution u = cos(x)
e) the substitution u = sin(x)

Can you please explain how you got the answer so that I can understand?
Thank you

d) the substitution u = cos(x)
Because du = sin(x) dx
integral (sin(x)^5)*(cos(x)^4) = integral (1-u^2)^2 * u^4 du