Standard answer for integral of cos(2deta)cos(ndeta)

[stan]

Hi

does anyone knows the standard answer for

integral of cos(2deta)cos(ndeta) from 0 to 180 degress?

for instance for integral of sin(ndeta)sin(deta) 0 to 180 degress, when n=1, it is 90 degress and when n not equals 1, it is 0...

thanks

 

[dvs]

Have you tried using integration by parts?

 

[Hurkyl]

What's a "deta" or an "ndeta"? What's your variable of integration?

You might want to review your trig identities... there's one that makes this kind of integral really easy.