to solve ∫ ( sin^3 x ) ( cos ^3 x ) dx, my lecturer said I must choose let u = cos x. Can anyone tell me why I cannot choose let u = sin x ?

Question

to solve ∫ ( sin^3 x ) ( cos ^3 x ) dx, my lecturer said I must choose let u = cos x.  Can anyone tell me why I cannot choose let u = sin x ?

anonymous · Answer

their just the same...

mr.math · Answer

You can!

anonymous · Answer

well,you should try it let u=sin(x),and see what you get

amistre64 · Answer

it so complex and convoluted that it can only be done in one specific way, otherwise it disintegrates

anonymous · Answer

I already try but the answer is not the same.

amistre64 · Answer

change cos^3 into: cos^2 cos 
                          (1-sin^2) cos

anonymous · Answer

sinx(1-cos^2x)(cos^3 x)dx

t=cosx
dt=-sinxdx

it transforms to

(1-t^2)(t^3)(-dt)

anonymous · Answer

they should have the same answer...

anonymous · Answer

yes

anonymous · Answer

okey I'll try again. thanks.

anonymous · Answer

keira... MAYBE YOU FORGOT THE NEEEEEGATTTTTIIIIIVVVVVVVVVVVEEEEEEEE????

amistre64 · Answer

thats what happens when you eat cheetos and use a keyboard :)

anonymous · Answer

no... watch one pis