If `5(tan^2x - cos^2x)=2cos 2x + 9`, then the value of cos4x is

If 5(tan^(2)x-cos^(2)x)=2cos2x+9, then the value of cos4x is: (2)/(9)(2)-(7)/(9)(3)-(3)/(5)(4)(1)/(3)

If 5(tan^(2)x-cos^(2)x)=2cos2x+9, then the value of cos4x is

5(tan^(2)x-cos^(2)x) = 2cos2x +9 , then the value of cos4x is:

If sin (x+y)=cos (x-y), then the value of cos^2x is :

If cos3x cos7x=cos^(2)2x, then general value of x is

If cos x+cos y=a and cos2x+cos2y=b then the value of cos x cos y=(lambda a^(2)+mu b-2)/(4) the value of 2 lambda-mu is

If cos3x.cos7x=cos^(2)2x, then general value of x is

If (sin x + cos x)/(sin x - cos x) = (6)/(5) , then the value of (tan^(2) x + 1)/(tan^(2) x-1) is :