Abramowitz&Stegun 9.6.34.
Edwin Woollett wrote:
> On Thu, 27 Nov 2008, Dan Stanger wrote
>
>> There is a trig identity which converts 4*a*b*(sin(x)+cos(x)) to
>> sqrt(2)*4*a*b*cos(x-atan2(a,b)).
>> Then the integrand can be expanded into I0(4*sqrt(2)*a*b)+ a sum
>> containing terms multiplied by cos(n*(x+atan2(a,b))
>> which when integrated between 0 and 2*pi give 0.
>
> Could you provide more details about the integrand being expanded
> into " I0(4*sqrt(2)*a*b)+ a sum containing terms multiplied by
> cos(n*(x+atan2(a,b)) " ?
>
> Ted Woollett
>
>