`cos4x cos8x-cos5xcos9x=0` if

cos4x cos8x-cos5x cos9x=0 if

0<=x<2 pi0<=x<2 pi ,then the number of real values of x, which satisfy the equation quad cos x+cos2x+cos3x+cos4x=0 is :(1)3(2)5(3)7(4)9

cos9x cos7x=cos5x cos3x; -pi/4 leq x leq pi/4

cos9x cos7x = cos5x cos3x [-pi/4 le x le pi/4]

prove that cos x cos2x cos4x cos8x=(sin16x)/(16sin x)

f(x)-cos5x+A cos4x+B cos3x+C cos2x+D cos xE and T-f(0)-f((pi)/(5))+f((3 pi)/(5))+......+f((8 pi)/(5))-f((9)/(4) then T

If g(x)=cos x cos2x cos4x cos8x then g'((pi)/(4))=

If f(x)=cos x cos2x cos4x cos8x cos16x then

The value of int_( sin )x cos x cos2x cos4x cos8x cos16x)dx is int(sin x cos x cos2x cos4x cos8x cos16x)dx is equal to

If f(x)=cos x cos2x cos4x cos8x cos16x then f'((pi)/(4)) equals